The 1.6 THP is the turbocharged direct-injection petrol engine that PSA and BMW developed together, fitted to Peugeot, Citroën and DS models and, as the N14 and N18, to the Mini Cooper S. It is strong and economical, but its timing chain and tensioner wear early, carbon builds up on the intake valves and some engines burn a lot of oil. Engines built up to about 2010 are the most troublesome; later ones are better but still need frequent oil changes and quick attention to any cold-start rattle. With proof of a chain kit and a careful owner it is a reasonable buy; without history it is a gamble.
At a glance
Displacement
1.6 L (1,598 cc), 4 cylinders, 16 valves
Power
About 150-210 hp in most versions
Generations
First series about 2006-2010 (EP6DT, EP6DTS, Mini N14); revised engines from 2010 (EP6CDT and later, Mini N18)
Timing drive
Chain with a hydraulic tensioner, no fixed change interval
Fuel system
Petrol direct injection with a camshaft-driven high-pressure pump, twin-scroll turbo
Weak spots
Timing chain and tensioner, carbon on the intake valves, oil consumption, thermostat housing
Cars with this engine
Make
Models
Years
Peugeot
207, 208, 308, 3008, 5008, 508, RCZ
2006-2018
Citroën, DS
C4, C4 Picasso, C5, DS3, DS4, DS5
2007-2018
Mini
Cooper S and John Cooper Works (R55 to R61): N14 engine up to 2010, N18 from 2010
2006-2016
BMW
114i, 116i, 118i and 316i with the N13 derivative
2011-2015
Known problems
Timing chain stretch and tensioner failure
What happens
The hydraulic chain tensioner runs on engine oil and, on early engines, loses its pressure after the car has been parked. For the first seconds after a cold start the chain slaps and rattles, which wears the chain and its guides until the chain stretches. A stretched chain throws the valve timing out and can jump a tooth, which can wreck the engine. The tensioner was revised several times; problems are much rarer on engines built from about 2014.
Symptoms
Rattle for a few seconds after a cold start
Engine warning light with camshaft timing codes
Rough running, hesitation or loss of power
Engine will not start after the chain has jumped
When
Early engines (about 2006-2010) sometimes from 30,000-50,000 km; later engines usually much later, at high mileage or after stretched oil-change intervals
Fitted cost
from €700 to €1,500
The fix
Replace the chain, tensioner, guides and sprockets with the latest parts and check the camshaft adjuster. If the chain has already jumped, the head or the whole engine may need rebuilding (roughly €2,000-6,000+).
The 1.6 THP injects fuel straight into the cylinders, so no fuel washes over the intake valves. Oil mist from the crankcase ventilation bakes onto the valves and ports as hard carbon, which restricts the airflow. Fuel additives do not reach these deposits.
Symptoms
Rough idle, especially from cold
Hesitation and misfires with a warning light
Gradual loss of power and higher fuel use
When
Builds up steadily with mileage; a clean every 50,000-60,000 km is the usual advice, sooner for cars used on short trips
Fitted cost
from €140 to €300
The fix
Clean the intake valves and ports (walnut blasting or a similar induction clean) and check the crankcase ventilation.
Some engines burn a lot of oil, up to about a litre every 1,500-2,500 km. A blocked crankcase ventilation system, carbon on the piston rings and, on high-output versions, damaged pistons are the usual causes. Running low on oil is dangerous on this engine: it speeds up camshaft wear and starves the chain tensioner.
Symptoms
Oil level dropping between services
Blue smoke at start-up or on hard acceleration
Misfires and fouled spark plugs
Low oil level warning
When
Any mileage, most often on early engines and on cars serviced at long intervals
Fitted cost
from €150 to €500
The fix
Start with the crankcase ventilation (the valve in the cam cover) and a compression test. If the rings or pistons are damaged, the fix is new pistons and rings or an exchange engine (roughly €2,000-6,000+).
The plastic thermostat housing is prone to cracking, especially on early engines, so coolant seeps out slowly. A thermostat that sticks open keeps the engine cold, while a falling coolant level can end in overheating, which a turbo engine does not forgive.
Symptoms
Coolant level dropping with no obvious puddle
Dried coolant traces or a sweet smell around the engine
Temperature gauge slow to rise, or rising too high
Engine warning light with a thermostat code
When
Any mileage; a frequent fault on this engine
Fitted cost
from €150 to €450
The fix
Replace the thermostat and its housing, then refill and bleed the cooling system.
The high-pressure fuel pump is driven by a camshaft and feeds the direct injectors. On early engines it could wear or fail, so fuel pressure drops under load and the engine loses power. A stretched timing chain can set similar faults, so it is checked first.
Symptoms
Loss of power or jerking under acceleration
Limp mode with a fuel pressure message
Long cranking or stalling
Engine warning light with a fuel rail pressure code
When
Mostly early engines, at any mileage
Fitted cost
from €250 to €800
The fix
Confirm the fault with manufacturer software and a check of the timing chain, then replace the high-pressure pump.
+Stored and pending engine codes such as P0016, P0011 and P0012 (camshaft timing), P0300 to P0304 (misfires), P0087 and P0191 (fuel rail pressure), P0128 (thermostat) and P0420 (catalyst)
+The freeze-frame snapshot saved with a code: engine speed, load, coolant temperature and speed at the moment it set
+Live coolant temperature, to see whether the engine warms up too slowly or runs hot
+Short- and long-term fuel trims and intake manifold pressure (MAP), which point to air leaks and mixture problems
+Readiness monitors: several incomplete monitors on a car for sale suggest the codes were cleared recently
Needs manufacturer-level software
−How far the timing chain has stretched: the camshaft deviation values workshops use are read with PSA or BMW software
−Oil consumption, piston condition or carbon on the intake valves
−Per-cylinder misfire counters and compression, which need manufacturer software and a compression tester
−Commanded versus actual high-pressure fuel values in the detail a workshop uses to condemn the pump
−Coolant leaks at the thermostat housing, which need a visual check
Buying checklist
Identify the engine: early engines are about 2006-2010 (EP6DT, EP6DTS, Mini N14); revised engines come from 2010 (EP6CDT and later, Mini N18). The engine code is in the documents or on the engine.
Start the engine fully cold (ideally parked overnight) and listen for a rattle in the first seconds.
Ask for an invoice for a timing chain kit with the tensioner, with date and mileage; a high-mileage car with its original chain should be priced for one.
Check the dipstick and ask how often oil is topped up; a low level or blue smoke points to oil consumption.
Look for short oil-change intervals and the oil specification from the service booklet, not the longest interval allowed.
Check the coolant level and look for dried coolant around the thermostat housing.
Scan for stored and pending codes and check the readiness monitors before the test drive.
On the test drive, the engine should pull smoothly from low revs without hesitation, misfires or a sudden loss of power.
Checking a car with this engine?
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Frequently asked questions
Is the 1.6 THP a reliable engine?
It is strong and economical, but not robust. The timing chain and tensioner, carbon on the intake valves and oil consumption all need watching, and engines built up to about 2010 are the weakest. A later engine with frequent oil changes and a replaced chain kit can be a good ownership proposition.
Which 1.6 THP years should you avoid?
The first series, roughly 2006 to 2010, has the worst record for chain and tensioner trouble. The revised engines from 2010 are better, and complaints became much rarer on engines built from about 2014. History matters more than the year: an early engine with a new chain kit and a careful owner beats a later one that was neglected.
How do I know if the 1.6 THP timing chain is stretched?
The classic sign is a rattle for a few seconds after a cold start, before the tensioner fills with oil. A stretched chain can also set camshaft timing codes such as P0016 or P0011. A workshop confirms it by reading the camshaft deviation with PSA or BMW software or by inspecting the chain.
Is the Mini Cooper S engine the same as the Peugeot 1.6 THP?
Yes. The Mini Cooper S of the R56 era uses the same PSA-BMW Prince engine, called N14 up to 2010 and N18 afterwards. The N14 shares the early engine's chain and carbon problems; the N18 is the revised engine and generally the better bet, though it still needs the same care.
How much oil does a 1.6 THP burn?
A healthy engine should need little oil between services, but some engines use up to about a litre every 1,500-2,500 km. Check the dipstick every couple of weeks and keep the level up, because running low accelerates camshaft wear and starves the chain tensioner.
When should the 1.6 THP timing chain be replaced?
The manufacturer sets no change interval for the chain. Because it wears on this engine, AutoCentrum's engine guide advises a preventive chain change about every 100,000 km, and straight away if the cold-start rattle appears.
