BMW N55 engine report
BMW N55 · 335i (E90/E92)
3.0 LPetrolInline-62010–2012
70/100
[good]
A calmer 335i than the N54, provided the oil was changed often
Worth buying, but only on the right car. Receipts for frequent oil changes, no oil weeping from the filter housing or valve cover, and no stored fault codes for the electric water pump.
ExcellentGoodSolidRiskyAvoid
- Known issues
- 16
- Critical
- 4
- Sources
- 76
Verdict
The service history decides whether this one is a good buy.
Rod bearing wear is very common and can end the engine. On this car it is mostly put down to long gaps between oil changes, so thin records make it a gamble. Oil leaks from seals and gaskets are the usual age repair, while the high-pressure fuel pump, the injectors and the water pump fail now and then. The oil pump, the timing chain and the wastegates give trouble rarely, and head gasket or ringland failures hardly ever happen. An oil analysis costs little next to a rebuild.
Specs
- Displacement
- 3.0 L2,979 cc
- Layout
- Inline-6
- Fuel
- Petrol
- Compression
- 10.2:1
- Production
- 2009–2021
- Chassis
- E90/E92
- Generation
- LCI N55
- Fitted
- 2010–2012
Known issues
16 confirmed · sorted by severity
CriticalRod bearing failure
Connecting rod (big end) bearing wear or spun bearing, usually from oil starvation or extended oil-change intervals -- can destroy the engine if not caught early.
Symptoms
- Knocking Noise
- Warning Light
How often
Very common · Owner-caused. Can destroy the engine if ignored. Not safely drivable.
Evidence
81 owner reports back this, confidence 45/100.
CriticalOil pump wear / sludge buildup
Oil pump wear or sludge accumulation (often from extended oil-change intervals) reducing oil pressure and lubrication.
Symptoms
- Warning Light
- Knocking Noise
How often
Rare · Owner-caused. Can destroy the engine if ignored. Not safely drivable.
Evidence
10 owner reports back this, confidence 45/100.
CriticalHead gasket failure
Head gasket failure, often preceded by overheating; can lead to a warped head or cracked block if not addressed.
Symptoms
- Coolant Loss
- Smoke (White/Blue/Black)
- Warning Light
How often
Very rare · Age-related wear. Does not normally destroy the engine. Not safely drivable.
Evidence
5 owner reports back this, confidence 45/100.
CriticalPiston ringland failure
Piston ringland cracking under high cylinder pressure/heat, common on tuned forced-induction engines.
Symptoms
- Power Loss
- Smoke (White/Blue/Black)
- Misfire
How often
Very rare · Design weakness. Can destroy the engine if ignored. Not safely drivable.
Evidence
2 owner reports back this, confidence 45/100.
HighHigh-pressure fuel pump failure
HPFP wear or failure, sometimes shedding metal debris into the fuel system.
Symptoms
- Misfire
- Warning Light
- Hesitation
How often
Occasional · Age-related wear. Does not normally destroy the engine. Not safely drivable.
Evidence
25 owner reports back this, confidence 45/100.
ModerateWater pump failure
Water pump seal or bearing failure (mechanical or electric pump), causing coolant loss.
Symptoms
- Coolant Loss
- Warning Light
How often
Occasional · Age-related wear. Does not normally destroy the engine. Still drivable.
Evidence
18 owner reports back this, confidence 60/100.
ModerateTiming chain stretch / guide wear
Timing chain elongates or plastic guides wear prematurely, causing rattle, incorrect valve timing, or in severe cases chain failure.
Symptoms
- Knocking Noise
- Cold Start Rattle
- Warning Light
How often
Rare · Age-related wear. Does not normally destroy the engine. Still drivable.
Evidence
12 owner reports back this, confidence 45/100.
ModerateExcessive oil consumption
Worn valve stem seals, piston rings, or a clogged PCV/oil separator system causing oil consumption above manufacturer spec.
Symptoms
- Oil Consumption
- Smoke (White/Blue/Black)
How often
Rare · Age-related wear. Does not normally destroy the engine. Still drivable.
Evidence
8 owner reports back this, confidence 45/100.
ModerateDual-mass flywheel / clutch wear
Dual-mass flywheel wear causing rattle/vibration, often coinciding with clutch replacement interval.
Symptoms
- Excessive Vibration
- Knocking Noise
How often
Very rare · Expected maintenance. Can destroy the engine if ignored. Still drivable.
Evidence
5 owner reports back this, confidence 40/100.
LowOil leak from seals or gaskets
Valve cover gasket, rear main seal, or front main seal degradation causing external oil leaks.
Symptoms
- Oil Consumption
How often
Common · Age-related wear. Does not normally destroy the engine. Still drivable.
Evidence
34 owner reports back this, confidence 60/100.
LowFuel injector failure
Injector wear, sticking, or seal failure causing misfires, rough running, or fuel leaks.
Symptoms
- Misfire
- Rough Idle
- Fuel Smell
How often
Occasional · Age-related wear. Does not normally destroy the engine. Still drivable.
Evidence
22 owner reports back this, confidence 45/100.
LowWastegate / boost actuator failure
Wastegate, boost control actuator, or diverter/blow-off valve failure causing boost leaks or inconsistent boost pressure.
Symptoms
- Reduced Power Mode
- Turbo Lag
How often
Rare · Age-related wear. Does not normally destroy the engine. Still drivable.
Evidence
10 owner reports back this, confidence 45/100.
LowThermostat / temperature sensor failure
Thermostat sticking open or closed, or temperature sensor drift, causing incorrect operating temperature.
Symptoms
- Warning Light
How often
Very rare · Age-related wear. Does not normally destroy the engine. Still drivable.
Evidence
5 owner reports back this, confidence 55/100.
LowIntake valve carbon buildup
Direct-injection engines lack fuel washing the intake valves, leading to carbon buildup, misfires, and reduced power over time.
Symptoms
- Misfire
- Power Loss
- Rough Idle
How often
Very rare · Expected maintenance. Does not normally destroy the engine. Still drivable.
Evidence
4 owner reports back this, confidence 45/100.
LowVariable valve timing solenoid/actuator failure
VANOS/VTEC/VVT-style variable valve timing solenoids or actuators fail or clog, causing rough idle, rattle on start, or reduced power.
Symptoms
- Rough Idle
- Reduced Power Mode
- Warning Light
How often
Very rare · Age-related wear. Does not normally destroy the engine. Still drivable.
Evidence
5 owner reports back this, confidence 45/100.
LowEngine sensor failure
Crankshaft, camshaft, MAP, lambda/O2, or MAF sensor failure causing rough running, stalling, or incorrect fueling.
Symptoms
- Warning Light
- Rough Idle
- Misfire
How often
Very rare · Age-related wear. Does not normally destroy the engine. Still drivable.
Evidence
5 owner reports back this, confidence 45/100.
- Critical
- High
- Moderate
- Low
Rod bearing failurefrom 97k km
High-pressure fuel pump failurefrom 97k km
Oil pump wear / sludge buildupfrom 97k km
Water pump failurefrom 89k km
Oil leak from seals or gasketsfrom 105k km
Head gasket failurefrom 97k km
Piston ringland failurefrom 89k km
Timing chain stretch / guide wearfrom 266k km
Showing the 8 highest-impact of 16 dated issues. The rest are in the list above.
Buying checklist
0 of 15 checked
Sources
Updated 12 Sept 2026 · scoring v2.7
Behind this report sit 76 owner posts, forum threads and official records. Nothing gets on the list on one person's word. It takes a recall, or owners on separate platforms describing the same fault. The score then sets how often a problem turns up against the damage it does.