On most inline four-cylinder engines it is the last cylinder, at the flywheel and gearbox end, because numbering starts at the crankshaft-pulley end. Peugeot and Citroen have traditionally numbered from the flywheel end, which puts cylinder 4 at the pulley end on their engines.

Can a three-cylinder engine set P0204?

No. A three-cylinder engine only has injectors 1 to 3, so it cannot report a cylinder 4 injector circuit. If a three-cylinder car shows P0204, read the codes again and check that the scan tool has identified the engine correctly.

Why does my inline-six show a bank 2 fuel trim with P0204?

Some inline-six engines with two front catalytic converters, BMW's N52 among them, split the cylinders into two groups for fuel control: 1 to 3 as bank 1 and 4 to 6 as bank 2. Cylinder 4 is the first cylinder of bank 2, so a dead cylinder 4 injector shows up in bank 2 trims.

Do I need to code a new cylinder 4 diesel injector?

Yes. Common-rail diesel injectors carry a correction code (called IMA, IQA or C2i depending on the supplier) that the engine computer uses for that cylinder. Without it the engine can smoke, knock or lose power. Generic OBD2 cannot write it, so use a brand tool or a workshop.

What does P0204 cost to repair?

Most fixes are a connector or wire, about 65-220 EUR at a workshop. A petrol injector fitted costs about 100-310 EUR, and a common-rail diesel injector about 250-650 EUR with coding.

Can I clear P0204 and keep driving?

Clearing it only switches the light off for a while. If the circuit is still open or shorted the code returns on the next drive, and the engine keeps running on one cylinder fewer in the meantime. Find and fix the fault first.

P0204: Injector Circuit / Open - Cylinder 4

Quick Answer

Safe to drive (short-term)

P0204 is the injector circuit code for cylinder 4: the engine computer measured an open, a short or an unexpected resistance in that injector's wiring. On an inline four-cylinder, cylinder 4 is the end cylinder next to the gearbox, and a three-cylinder engine cannot set this code at all. A connector or wiring fix usually costs about 65-220 EUR at a workshop; a petrol injector fitted about 100-310 EUR.

Severity: Moderate · Fuel System
Estimated repair cost: From €5 to €650+, varies by vehicle

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What does P0204 mean?

P0204 is a fuel system-related diagnostic trouble code classified as moderate severity.

What are the symptoms of P0204?

Check engine light, flashing if the misfire is heavy
Lumpy idle and vibration through the car
Hesitation when you press the accelerator
Reduced power, most obvious at higher load
Smell of petrol or sulphur from the exhaust
On V6 engines, a lean reading or positive fuel trim on bank 2

What causes P0204?

Corroded, loose or damaged connector on the cylinder 4 injector at the gearbox end of the head
: high
Wiring fault in the cylinder 4 branch of the injector harness
: high
Cylinder 4 injector coil open or shorted
: medium
Fault on the supply all injectors share: fuse, relay or ground
: medium
Injector 4 driver inside the engine control unit has failed
: low

Is it safe to drive with P0204?

Generally yes, for short-term driving. A gentle drive to a workshop is usually possible, but cylinder 4 is not being fuelled correctly and the engine is effectively running on one cylinder fewer. Avoid hard acceleration and long trips, and stop if the check engine light begins to flash, because the catalytic converter is then overheating.

How do you diagnose P0204?

Use Skanyx to read P0204 with its freeze frame and list the other codes stored: P0304 (cylinder 4 misfire), P0270 or P0271 (cylinder 4 injector circuit low or high) and any lean code for the bank concerned
Locate cylinder 4. On an inline four-cylinder it is the last cylinder, at the flywheel and gearbox end (at the pulley end on Peugeot and Citroen engines, which traditionally number the other way). On a V6 it is on bank 2 under both common numbering schemes. On BMW's N52 inline-six it is the first cylinder of the group the engine computer treats as bank 2
Check the cylinder 4 injector plug and the last stretch of harness running to it. At the gearbox end the loom is clipped close to the engine, so look for chafing at clips and brackets as well as corrosion in the plug
Measure the injector coil at its pins with the ignition off, then from the ECU pin for injector 4 to include the wiring. Compare both readings with the value for your engine
If the injector and the wiring both measure correctly, have the injector signal checked with a noid light on port injection, or with an oscilloscope on direct-injection and diesel engines, whose injectors run at high voltage
Swap injector 4 with injector 3, clear the code and drive. A code that moves to P0203 points to the injector; P0204 returning points to the wiring or the ECU
A replacement common-rail diesel injector has to be coded to the cylinder 4 position with its correction code, which generic OBD2 cannot do. Budget for a brand tool such as Carly, OBDeleven or XENTRY, or have a workshop do it

How much does P0204 cost to fix?

Repair	Parts Cost	Labor Cost	Total Estimate	DIY Difficulty
Repair the cylinder 4 connector or wiring at home (DIY)	€5–€30	€0–€0	€5–€30	Moderate
Workshop repair of the cylinder 4 injector circuit	€5–€40	€60–€180	€65–€220	Professional
New cylinder 4 injector, petrol, workshop fitted	€40–€150	€60–€160	€100–€310	Moderate
New cylinder 4 injector, common-rail diesel, workshop fitted and coded	€150–€400	€100–€250	€250–€650	Professional

Prices estimated as of October 2026. Costs vary by region, vehicle, and shop.

Engines known for this code

P0204 on specific vehicles

P0204 on Volkswagen

Volkswagen Golf

See Volkswagen-specific causes & cost

P0204 on BMW

BMW 3 Series

See BMW-specific causes & cost

P0204 on Ford

Ford Focus

See Ford-specific causes & cost

P0204 on Mercedes-Benz

Mercedes C-Class

See Mercedes-Benz-specific causes & cost

P0200
P0270
P0271
P0272
P0304
P0174
P0203

Common questions about P0204

Where is cylinder 4?: On most inline four-cylinder engines it is the last cylinder, at the flywheel and gearbox end, because numbering starts at the crankshaft-pulley end. Peugeot and Citroen have traditionally numbered from the flywheel end, which puts cylinder 4 at the pulley end on their engines.
Can a three-cylinder engine set P0204?: No. A three-cylinder engine only has injectors 1 to 3, so it cannot report a cylinder 4 injector circuit. If a three-cylinder car shows P0204, read the codes again and check that the scan tool has identified the engine correctly.
Why does my inline-six show a bank 2 fuel trim with P0204?: Some inline-six engines with two front catalytic converters, BMW's N52 among them, split the cylinders into two groups for fuel control: 1 to 3 as bank 1 and 4 to 6 as bank 2. Cylinder 4 is the first cylinder of bank 2, so a dead cylinder 4 injector shows up in bank 2 trims.
Do I need to code a new cylinder 4 diesel injector?: Yes. Common-rail diesel injectors carry a correction code (called IMA, IQA or C2i depending on the supplier) that the engine computer uses for that cylinder. Without it the engine can smoke, knock or lose power. Generic OBD2 cannot write it, so use a brand tool or a workshop.
What does P0204 cost to repair?: Most fixes are a connector or wire, about 65-220 EUR at a workshop. A petrol injector fitted costs about 100-310 EUR, and a common-rail diesel injector about 250-650 EUR with coding.
Can I clear P0204 and keep driving?: Clearing it only switches the light off for a while. If the circuit is still open or shorted the code returns on the next drive, and the engine keeps running on one cylinder fewer in the meantime. Find and fix the fault first.

Read our detailed guides

Scan your car with Skanyx to diagnose P0204