What is the difference between BMW N47 and B47 engines on the 320d?

The N47 (2007 to 2014-2015) and the B47 that replaced it are both 2.0 litre turbocharged diesel four-cylinder engines for the BMW 320d. The difference that matters to a buyer is the timing chain. The N47 carries its chain at the rear of the engine, against the bulkhead, and it is prone to excessive wear and failure, worst on engines built between March 2007 and January 2009; replacing it is an engine-out job. The B47 has a redesigned chain drive, and chain failures are far rarer. Both engines have had EGR cooler recalls, so ask a BMW dealer to check the VIN for open recall work. For a used buyer, the B47 is the safer choice at almost any price point.

How do I check the BMW 320d N47 timing chain before buying?

Two checks you can do yourself and one you pay for. First, listen at a genuine cold start. Ask the seller not to warm the car up before you arrive, open the bonnet, then start the engine from stone cold. A healthy chain makes no audible rattle. A worn one produces a metallic rattle for one to two seconds in the first five seconds after start, coming from the rear of the engine behind the cylinder head, and it fades as oil pressure builds. Second, look through the service history for a documented chain replacement and the mileage it was done at. Third, read the stored codes: a crankshaft-to-camshaft correlation or camshaft sensor code ([P0016](/codes/p0016), [P0340](/codes/p0340)) on an N47 is a chain warning, and a BMW specialist can inspect further before you commit.

Should I buy an F30 (2012-2019) or G20 (2019 onward) BMW 320d?

G20 if the budget allows. The F30 is widely available with the B47 from the 2015 facelift onward and prices start around 13,000 EUR. The G20 has the later B47 with AdBlue, and prices start around 19,000 EUR. A facelifted F30 with the B47 already avoids the N47 chain problem, while a pre-facelift F30 still has the N47 and its chain risk. Beyond the engine, the F30 carries ordinary platform ageing on trim and the infotainment. For the most reliability per euro spent, a 2017 or 2018 F30 320d with a B47 engine and a verified emissions history is the sweet spot.

What is the ZF 8HP mechatronic and how do I check it?

The ZF 8HP is the eight-speed automatic gearbox used on the BMW 320d from the F30 (2012) onward; the older E90 used a ZF six-speed. The mechatronic is the control pack that lives inside the gearbox and decides every shift. Wear shows on high-mileage cars, especially where the fluid was never changed, and the tell is gear shift hesitation between 30 and 70 km/h on light throttle, occasional harsh downshifts, and a brief flare where the engine revs surge during an upshift. To check it, drive the car for 20 km in mixed traffic at varying loads and watch what happens at a 30 to 70 km/h cruise. A healthy 8HP shifts so smoothly you barely notice. Replacement costs 1,800 to 3,200 EUR at a BMW specialist, and some specialists rebuild the existing pack for 800 to 1,500 EUR.

How serious is the N47 timing chain problem on a used 320d?

Serious enough to be the single biggest reason to prefer a B47 over an N47 (built 2007 to 2014-2015). The N47 carries its timing chain at the rear of the engine, which means the engine has to come out to replace it, which is why an independent workshop quotes about 1,500 to 2,500 EUR and a BMW dealer more. The classic symptom is a metallic rattle lasting one to two seconds in the first five seconds after a cold start. An original chain on a high-mileage N47 can have stretched enough to rattle even when no codes are stored. The B47's redesigned chain drive rarely needs attention; if it ever does, specialists quote roughly 1,800 to 2,700 EUR, more on xDrive cars. If you are buying an N47, treat the chain as either already done with paperwork or as a cost coming your way.

Used BMW 320d Buyer's Guide: N47 vs B47, Faults and OBD2 Checks

The 320d splits at the engine. The N47 hides its chain at the back, a 1,500 to 2,500 EUR job at an independent. Here is how to tell which one you have.

Skanyx TeamUpdated September 2, 202610 min read

The short answer

Safe to drive

The used 320d splits at the engine, and that split is the whole decision. Cars built up to the 2014-2015 changeover use the N47, whose timing chain sits at the back, is prone to wear and costs 1,500 to 2,500 euros to replace at an independent; the B47 that followed rarely has the problem. Start the car from stone cold, listen for a rattle in the first five seconds, then read the stored codes.

How urgent: Before you buy
Likely cost: 1,500 to 2,500 EUR at an independent if the N47 chain is due, 1,800 to 3,200 EUR if the automatic gearbox pack is worn
First step: Ask the seller not to warm the car up, then start it from stone cold and listen for a metallic rattle in the first five seconds.

Key Takeaways(5)

The used 320d splits at the engine. The N47 (2007 to the 2014-2015 changeover) carries a failure-prone timing chain at the back of the engine; the B47 that replaced it has a redesigned chain drive that rarely gives trouble
That chain is the single biggest risk on the platform: about 1,500 to 2,500 EUR at an independent workshop on an N47, because the engine has to come out to reach it
The automatic gearbox control pack is the second. Wear shows on high-mileage cars as hesitation long before any code stores
Start the car from stone cold and listen for a metallic rattle in the first five seconds. That one check tells you more than any scan
Read the stored codes before you talk about money. Five checks separate a healthy car from one that costs you 5,000 EUR in the first year

In this article(12)

1Should you buy an N47 or a B47 320d?
2What could it cost you after you buy?
3What should you check at the viewing?
4How serious is the N47 timing chain problem?
5Two engine generations, two different cars
6The five checks worth running on the car
7Which faults should you expect to pay for?
8Should you buy the manual or the automatic?
9What is a used 320d worth in your country?
10How do you use the findings to negotiate?
11What does the OBD2 scan not catch?
12Start it cold, then talk about money

A 2017 BMW 320d xDrive on autoplius.lt shows 152,000 kilometres, a full service history and a price of 16,800 euros. The seller in Hamburg calls it excellent and says a recent cleaning service fixed everything. The dashboard is clean, the test drive feels smooth, and a basic scan returns no stored codes. None of that answers the two questions that decide whether this car is a bargain or a 5,000 euro problem.

Should you buy an N47 or a B47 320d?

Buy the B47 if you can, which in practice means a 2015 or later car, and check the engine code on anything built in 2014 or 2015. It is the same car with the expensive design flaw taken out of it.

Three things change that answer.

The N47 price already reflects the risk. These cars usually sit 2,000 to 3,000 euros below an equivalent B47. That is a rational buy if you have the chain money set aside and you are not pretending the risk is not there.
The chain has documented paperwork. A replacement invoice, with the mileage it was done at, turns the biggest risk on the platform into a solved problem. The fewer kilometres the new chain has covered since, the more life it has left.
The car is an automatic with high mileage. Then the gearbox matters more than the engine generation, and the test drive matters more than the scan.

The 2017 model year in the listing above sits after the changeover, so it should be a B47. Should is not the same as is, and the plate year is not the build date. Read the engine off the car before you read it off the advert.

What could it cost you after you buy?

These are the bills that turn up on used 320d examples, with rough forecasts at an independent BMW specialist. They are not quotes, and dealer pricing runs at the top of every row.

Likely fault	What it usually costs to put right	When it usually shows up
Rear timing chain, N47 only	1,500 to 2,500 euros at an independent, engine out	Original chains on high-mileage cars, worst on 2007-2009 builds
Timing chain, B47	Roughly 1,800 to 2,700 euros, more on xDrive	Rare
Automatic gearbox control pack	1,800 to 3,200 euros new, 800 to 1,500 rebuilt	High mileage, sooner on never-changed fluid
Cracked exhaust gas cooler	550 to 1,400 euros all in	N47 and B47; check the recall work
Blocked soot filter	150 to 600 euros to clean, 700 to 1,500 for an aftermarket filter	Short-trip cars, any mileage
The four glow plugs plus their control unit	350 to 700 euros for the set	Any age; they are wear parts
Leaking seals where fuel enters the engine	480 to 850 euros for a four-cylinder reseal	Older, high-mileage engines
Carbon on the intake swirl flaps, N47	350 to 650 euros to have them dealt with	Check the invoices; many have been done

Two things move these numbers. Whether an independent BMW specialist or a main dealer does the work, which is often a gap of a third. And whether the cheap causes get ruled out before anyone quotes for the expensive one.

What should you check at the viewing?

Start it from stone cold and listen. Ask the seller in advance not to warm the car up. Open the bonnet, stand at the back of the engine, and start it. A metallic rattle for a second or two, fading as the oil pressure builds, is the chain telling you what it is worth. This check costs nothing and outranks everything else on this page.
Plug in and read the stored codes. Any 15 to 30 euro Bluetooth adapter fits the socket under the dash, and an app on your phone reads the codes in about a minute and decodes the car's own build data, so you learn the engine and gearbox from the car rather than the advert. Read pending codes as well as stored ones, because a seller who cleared the dash this morning has not cleared those.
Drive it 20 km in mixed traffic and watch the gearbox. On an automatic, hold a light-throttle cruise between 30 and 70 km/h. Shifts should be almost invisible. Any hesitation or jolt at the change is wear in the control pack, and it appears long before any code stores.
Read the paperwork, then decide with what you found. Match the service stamps against the mileage. Look for a chain invoice on an N47 and a gearbox oil change on an automatic. A clean scan plus a clean cold start plus accurate paperwork is a car worth its asking price. Any one of the three missing is a number off the price, not a reason to panic.

How serious is the N47 timing chain problem?

Serious enough to split the used market in two. It is the reason an N47 and a B47 of the same age and mileage carry different prices.

The N47 engine drives its camshafts from a chain at the back of the engine, next to the flywheel and against the bulkhead. The chain, its tensioner and the plastic guides that hold it in line all wear, and at very different rates depending on how the car was driven and how often the oil was changed. Engines built between March 2007 and January 2009 were the worst; BMW revised the design, but failures continued at a lower rate.

When a guide snaps it releases tension on the chain. The chain then jumps teeth or breaks, and the pistons meet the valves. That is the end of the engine, and there is no gentle version of it.

The warning signs arrive weeks or months earlier:

A metallic rattle at cold start, lasting one to three seconds, coming from the rear of the engine
Noticeably less pull at the top of the rev range as the valve timing drifts
Stored crankshaft-to-camshaft correlation or camshaft sensor codes on an ordinary scan, such as P0016, P0017, P0340 or P0341

The fix at that point is a preventive chain replacement, about 1,500 to 2,500 euros with labour at an independent BMW specialist, and more at a BMW dealer. Most of that is access: the engine comes out, or a large part of the front of the car does.

For a buyer, the only question is whether it has been done. Look in three places. The service history, for a chain replacement entry. The mileage at which it was done, because a chain replaced at 90,000 km has far more life left than an original one at 180,000 km. And the cold start, which is the check no paperwork can fake.

If an N47 320d still has its original chain past 150,000 km and rattles at all on a cold start, walk away unless the price has 2,500 euros of chain work already taken off it.

Two engine generations, two different cars

Spec	N47 (2007 to 2014-2015)	B47 (2015 onward in the 320d)
Body platform	E90 (2007-2012) plus pre-facelift F30 (2012-2015)	F30 facelift (2015-2019) plus G20 (2019 onward)
Emissions standard	Euro 4 and Euro 5, Euro 6 on some late cars	Euro 6, Euro 6d-Temp, Euro 6d
Timing chain	Rear of engine, against the bulkhead; prone to wear	Redesigned chain drive; failures rare
Chain replacement cost	1,500-2,500 EUR at an independent (engine out)	Roughly 1,800-2,700 EUR, more on xDrive
Exhaust gas cooler	Recalled over leaks and fire risk	Also recalled; check the VIN for open work
Exhaust fluid (AdBlue) system	No on Euro 5; check late Euro 6 cars for an AdBlue filler	Added in a 2017 update; the G20 has it, earlier F30s may not (look for the filler)
Power options	177 hp (E90 to 2010), 184 hp (most common later), 163 hp (EfficientDynamics)	190 hp (F30 facelift and G20)
Gearbox options	6-speed manual; ZF six-speed automatic (E90), ZF 8HP (F30)	6-speed manual, ZF 8HP automatic
Typical used price (EU)	8,000-14,000 EUR	13,000-18,000 EUR (F30 facelift), 19,000-28,000 EUR (G20)
Known weak points	Rear chain wear, EGR cooler recall, intake swirl flap carbon	Soot filter on short trips, gearbox control pack, EGR cooler recall
Best for	Buyers pricing in a chain replacement	Buyers who want the lower risk

The B47 is the safer choice at any mileage. An N47 is still a rational buy when the price reflects the chain risk and you have the money set aside for it. For most people, a 2017 or 2018 F30 with the B47 is the sweet spot: old enough to have taken its depreciation, new enough to have left the N47 chain problem behind.

Walking up to a Hamburg driveway with a full service history in one hand and no way to check it is exactly the moment a pocket mechanic earns its keep. The Skanyx Pre-Purchase Inspection runs the car through eight structured steps: preparation, an initial code scan, 90 seconds at idle, a 75-second cruise, 45 seconds of acceleration, a final code scan, a fraud check for recently cleared codes and incomplete self-tests, then a multi-specialist analysis. It ends on a plain verdict, buy, negotiate, treat with caution or walk away, with a 0 to 100 score, itemised findings, repair-cost estimates and a negotiation script in a PDF you can hand to the seller. BMW-only data, such as the gearbox control pack's own readings, still needs a BMW-specific tool like BimmerLink or Carly for BMW. Run it on the 320d you are about to buy

The five checks worth running on the car

Sequenced cheapest first. Stop and renegotiate, or walk away, if any one of them fails clearly.

1. The soot filter

What any generic adapter gives you: stored and pending filter codes, P2002, P244A and P244B, with the snapshot saved beside each one, plus the emissions self-test status. A stored P2002 on a car the seller calls fault-free is enough to renegotiate without going any deeper.

What needs a BMW-aware tool: the lifetime cleaning-cycle count and the current soot load in grams. The time since the last cycle, too. Those live on Mode $22 manufacturer-extended data that generic OBD2 does not expose. Use Carly for BMW or BimmerLink, or pay an independent specialist 30 to 60 euros for an ISTA session.

BMW publishes no buyer-facing reference table for these values, so read them against the specialist's judgement and the car's mileage. What you want is a count that rises with the mileage and a soot load that drops after a long motorway run. A high-mileage car showing a count near zero points at a deleted filter, a reset control unit, or edited software that suppresses the cleaning cycle. Our delete detection guide covers the follow-up.

2. Cam timing codes and the recycling valve

A generic adapter pulls stored, pending and permanent codes from the engine computer. On an N47 the crankshaft-to-camshaft correlation and camshaft sensor codes matter most: P0016, P0017, P0340 and P0341. Any of those stored is a possible chain wear signal, and you get it from the cheap scan alone.

On a B47 those codes are rarer, and the valve that recycles exhaust gas back into the engine (the EGR valve) is the more useful check. A generic scan returns stored codes, P0401, P0402 and P0404, with the snapshot beside each. Comparing what the car asked that valve to do against what it actually did is BMW-only data, sampled at idle and at a 2,000 rpm cruise with a BMW-aware tool. On a healthy system actual follows commanded closely, and a large or persistent lag points at carbon build-up, which is the same mechanism behind a stored insufficient flow code. Our delete detection guide for that valve covers the rest.

3. Exhaust fluid on Euro 6 cars

Later B47 engines, including every G20 320d, use exhaust fluid (AdBlue) to meet the nitrogen oxide limits; on an older car, the blue filler cap tells you. What a generic scan gives you: stored and pending codes on that system, including P20EE for SCR catalyst efficiency below threshold, plus the countdown warning on the dashboard. Any of those stored is enough on its own to pause the deal.

What needs a BMW tool: the dosing rate and the live sensor readings either side of the converter. BMW publishes no buyer-facing dosing figures, so the test is whether dosing happens at all: at a steady motorway cruise it should be present and should move with load.

Zero dosing, or a value that never moves at all, points at tampering. Our tampering check guide covers the full load-phase test.

4. Coolant temperature stability

Read the coolant temperature on live data through 15 minutes of mixed driving. This is a cheap check that catches a thermostat fault.

What you should see	What it means
Close to the outside temperature at a cold start, then rising steadily	Normal
Reaches about 90 degrees during a 10 to 15 minute drive	Normal
Holds roughly steady around that figure in traffic and on a cruise	Normal
Swings widely, or climbs past about 105 degrees	Cooling fault, thermostat first
Never reaches normal temperature on a proper drive	Thermostat fault, often a stuck-open unit

A genuine cold-start reading also proves the car really was cold for your chain listen test.

5. The automatic gearbox test

This is the most important check on an automatic 320d, and no scanner performs it. You do, with 20 km of mixed driving.

A light-throttle cruise between 30 and 70 km/h. Shifts should be almost invisible. Any hesitation or jolt at the change point is wear in the control pack.
An upshift under acceleration. It should be smooth and immediate. A brief flare, where the engine revs surge during the change, points at clutch wear inside the gearbox.
A coast down from 90 to 40 km/h. Downshifts should pass unnoticed. Harsh ones point back at the same control pack.

Wear shows on high-mileage cars, sooner where the fluid was never changed. Replacement runs 1,800 to 3,200 euros at a BMW specialist, and some specialists rebuild the existing pack for 800 to 1,500 euros with similar durability. A seller with a hesitating gearbox usually knows, so use the repair cost as the anchor.

Which faults should you expect to pay for?

Four faults dominate the used 320d service market beyond the chain question, and each has a known price, which is what makes them plannable rather than nasty.

Carbon on the intake swirl flaps, N47. The N47 intake uses small swirl flaps that adjust airflow, and they collect carbon until the linkage wears. In the worst case a flap breaks free and is drawn into the engine, which ends badly. Many cars have had the flaps dealt with already, a one-off job at 350 to 650 euros. Look for the invoice; if it has not been done, price it in.

Cracked exhaust gas cooler. BMW has recalled N47 and B47 diesels more than once over EGR coolers that can leak coolant, which mixed with soot and heat can start a fire, so ask a BMW dealer to check the VIN for open recall work. Outside a recall, budget 550 to 1,400 euros all in. The tells:

White smoke under acceleration
Coolant disappearing with no visible leak
Occasional misfire codes such as P0301 to P0304 under sustained load

Glow plugs. These are wear parts on any diesel. Replace all four together, with the control unit if it has failed, 350 to 700 euros, because replacing one is false economy. The tells:

Hard starting below 5 degrees
A cloud of white smoke that clears within 30 seconds
Stored circuit codes P0671 to P0674

Leaking seals where fuel enters the engine. The seals at the base of each injector harden and weep on older, high-mileage engines. A four-cylinder reseal runs 480 to 850 euros all in. It is a moderate job for an experienced home mechanic and a routine one for a specialist. The tells:

A diesel smell around the engine bay
Oily contamination at the cylinder head
A rough patch on one cylinder

Should you buy the manual or the automatic?

The F30 320d came with a 6-speed manual or the ZF 8HP automatic, and the 8HP carried over to the G20; check which the car in front of you has, because most used examples are automatics.

ZF 8HP automatic	6-speed manual
Daily driving	Shifts you barely notice, no clutch fatigue in traffic	More involving, more work in a queue
Motorway economy	Better, because eighth gear drops the revs at 130 km/h	Slightly worse
Acceleration	Quicker than a driver can shift the same engine	Slower
The big risk	Control pack, 1,800 to 3,200 EUR on a high-mileage car	Clutch and dual-mass flywheel, 1,500 to 2,500 EUR
Servicing	No fixed interval from BMW, but ZF recommends a fluid change after hard use or unknown history; 250 to 350 EUR	Usually none specified
Purchase price	Typically 500 to 1,500 EUR above the manual	Lower
Resale	Easier, especially on 190 hp xDrive cars	Harder on premium trims

The automatic is the right buy for urban or motorway duty, where the smoothness is worth the control pack risk. The manual is the right buy if you want the lower long-term cost and do not mind the extra work.

What is a used 320d worth in your country?

Germany. mobile.de and autoscout24.de carry thousands of examples at any time, mostly F30. Germany also has the deepest specialist network for both the chain job and a gearbox pack rebuild.

Poland. otomoto.pl and olx.pl carry a large supply, mostly imported from Germany. Warsaw and Wrocław have established BMW diesel specialists.

Lithuania. autoplius.lt and autogidas.lt carry a steady supply. Vilnius and Kaunas both have BMW-aware specialists, and gearbox pack rebuilds are available locally. N47 examples sit lower on price, where the chain risk hurts buyer confidence.

Spain. coches.net and autocasion.com carry a good supply.

United Kingdom. Imports are expensive after Brexit and the domestic market is steady. Right-hand drive limits cross-border arbitrage in both directions.

How do you use the findings to negotiate?

Every check above turns into a number you can name. The wording to use on the day is in our guide to negotiating a used car price with OBD2 evidence.

Cold-start rattle confirmed on an N47. Anchor on the 1,500 to 2,500 euro chain job at an independent specialist. Most sellers will not meet the full figure, but 1,000 to 1,500 euros off is rational on a car the seller knows is near the end of a chain.
Gearbox hesitation confirmed. Anchor on 1,800 to 3,200 euros for a new pack, or 800 to 1,500 for a rebuild. A reduction of 1,000 to 1,500 euros is typical.
Cleaning-cycle count implausibly low for the mileage. Anchor on the cheaper of the two filter numbers, an off-vehicle clean at 150 to 600 euros.
White smoke plus disappearing coolant. Check for an open recall first; otherwise anchor on 550 to 1,400 euros for the cooler, and walk if the seller resists.
Zero exhaust fluid dosing on a Euro 6 car. Walk away. Tampering plus the legal exposure plus the restoration cost beats any discount on offer.

What does the OBD2 scan not catch?

A generic scan on a 320d covers stored codes, the snapshot beside each one, the emissions self-tests and live engine data. Six things it will not tell you:

Chain wear on an N47 before codes set, which is what the cold-start listen is for
Gearbox control pack wear before codes set, which is what the 20 km drive is for
Glow plug condition without a stored code, which is what the cold-start smoke tells you
Carbon on the intake swirl flaps, visible only with the intake off
Weeping seals at the injectors, visible only with a torch in the engine bay
Body, structure and trim condition, which is a walk-round job

What covers the gap is a 30 minute drive from a genuine cold start through town and a short motorway run, plus a physical inspection at a BMW specialist for 150 to 300 euros. Our pre-purchase inspection guide sets out the full workflow, and for everything that is not engine-specific, from panel gaps to paperwork, follow the used car checking walkthrough alongside it.

Start it cold, then talk about money

So before you say anything about the price of that Hamburg 320d, ask the seller to leave it standing overnight and start it in front of you from stone cold. A rattle in the first five seconds is worth up to 2,500 euros of your money and no scanner will tell you about it. Read the codes afterwards, and let the two answers together decide whether you negotiate or walk.

Codes mentioned: P0016, P0017, P0340, P0341, P2002, P244A, P244B, P0401, P0402, P0404, P20EE, P0301, P0304, P0671, P0674.

Frequently Asked Questions

What is the difference between BMW N47 and B47 engines on the 320d?: The N47 (2007 to 2014-2015) and the B47 that replaced it are both 2.0 litre turbocharged diesel four-cylinder engines for the BMW 320d. The difference that matters to a buyer is the timing chain. The N47 carries its chain at the rear of the engine, against the bulkhead, and it is prone to excessive wear and failure, worst on engines built between March 2007 and January 2009; replacing it is an engine-out job. The B47 has a redesigned chain drive, and chain failures are far rarer. Both engines have had EGR cooler recalls, so ask a BMW dealer to check the VIN for open recall work. For a used buyer, the B47 is the safer choice at almost any price point.
How do I check the BMW 320d N47 timing chain before buying?: Two checks you can do yourself and one you pay for. First, listen at a genuine cold start. Ask the seller not to warm the car up before you arrive, open the bonnet, then start the engine from stone cold. A healthy chain makes no audible rattle. A worn one produces a metallic rattle for one to two seconds in the first five seconds after start, coming from the rear of the engine behind the cylinder head, and it fades as oil pressure builds. Second, look through the service history for a documented chain replacement and the mileage it was done at. Third, read the stored codes: a crankshaft-to-camshaft correlation or camshaft sensor code ([P0016](/codes/p0016), [P0340](/codes/p0340)) on an N47 is a chain warning, and a BMW specialist can inspect further before you commit.
Should I buy an F30 (2012-2019) or G20 (2019 onward) BMW 320d?: G20 if the budget allows. The F30 is widely available with the B47 from the 2015 facelift onward and prices start around 13,000 EUR. The G20 has the later B47 with AdBlue, and prices start around 19,000 EUR. A facelifted F30 with the B47 already avoids the N47 chain problem, while a pre-facelift F30 still has the N47 and its chain risk. Beyond the engine, the F30 carries ordinary platform ageing on trim and the infotainment. For the most reliability per euro spent, a 2017 or 2018 F30 320d with a B47 engine and a verified emissions history is the sweet spot.
What is the ZF 8HP mechatronic and how do I check it?: The ZF 8HP is the eight-speed automatic gearbox used on the BMW 320d from the F30 (2012) onward; the older E90 used a ZF six-speed. The mechatronic is the control pack that lives inside the gearbox and decides every shift. Wear shows on high-mileage cars, especially where the fluid was never changed, and the tell is gear shift hesitation between 30 and 70 km/h on light throttle, occasional harsh downshifts, and a brief flare where the engine revs surge during an upshift. To check it, drive the car for 20 km in mixed traffic at varying loads and watch what happens at a 30 to 70 km/h cruise. A healthy 8HP shifts so smoothly you barely notice. Replacement costs 1,800 to 3,200 EUR at a BMW specialist, and some specialists rebuild the existing pack for 800 to 1,500 EUR.
How serious is the N47 timing chain problem on a used 320d?: Serious enough to be the single biggest reason to prefer a B47 over an N47 (built 2007 to 2014-2015). The N47 carries its timing chain at the rear of the engine, which means the engine has to come out to replace it, which is why an independent workshop quotes about 1,500 to 2,500 EUR and a BMW dealer more. The classic symptom is a metallic rattle lasting one to two seconds in the first five seconds after a cold start. An original chain on a high-mileage N47 can have stretched enough to rattle even when no codes are stored. The B47's redesigned chain drive rarely needs attention; if it ever does, specialists quote roughly 1,800 to 2,700 EUR, more on xDrive cars. If you are buying an N47, treat the chain as either already done with paperwork or as a cost coming your way.

Quick reference

This article covers these diagnostic codes. Tap any code for a detailed breakdown with causes, costs, and vehicle-specific fixes:

Sources

Skanyx Team

Skanyx engineering team

Skanyx is written by the engineers who build the app and keep two BMWs of their own on the road, an E60 535d and a pre-facelift E61 535. Content is drafted with AI assistance and edited by the team. Repair-cost ranges are compiled from published parts prices, workshop price lists and repair-cost guides and rounded, fault codes follow the SAE definitions, and where a figure comes from a specific study or vendor page, the post lists it under Sources.

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