BMW B58 engine report, M340i G20
BMW B58 · M340i (G20)
3.0 LPetrolInline-62019–2025
91/100
Checked by hand
[excellent]
Among the best, if the oil pump checks out
Worth buying if the service history checks out.
ExcellentGoodSolidRiskyAvoid
- Known issues
- 12
- Critical
- 4
- Sources
- 100
Verdict
One entry dominates this record: oil pump wear and sludge, logged as critical and very common, though our confidence in it is low enough that the verdict stays uncertain.
Treat it as the thing to have inspected rather than a reason to walk. The water pump is a genuine common failure as mileage climbs. Injectors, the high-pressure fuel pump, VVT solenoids, the wastegate actuator and oil weeping from seals are occasional and unremarkable for the age. Rod bearings, ringlands and head gaskets are rare, and a service history plus a proper inspection is how you buy around them.
Specs
- Displacement
- 3.0 L2,998 cc
- Layout
- Inline-6
- Fuel
- Petrol
- Compression
- 10.2:1
- Production
- 2015–present
- Chassis
- G20
- Fitted
- 2019–2025
Known issues
12 confirmed · sorted by severity
CriticalOil pump failure
The oil pump stops delivering full pressure. The oil-pressure warning comes on, and if the engine keeps running, the bearings and turbo are starved of oil within minutes.
Symptoms
- Warning Light
- Knocking Noise
How often
Very common · Owner-caused. Can destroy the engine if ignored. Not safely drivable.
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
Rare · Design weakness. Can destroy the engine if ignored. Not safely drivable.
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 rare · Owner-caused. Can destroy the engine if ignored. Not safely drivable.
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
1 owner report backs this, confidence 40/100.
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
15 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
Common · Age-related wear. Does not normally destroy the engine. Still drivable.
Evidence
29 owner reports back this, confidence 50/100.
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. Does not normally destroy the engine. Still drivable.
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. Can destroy the engine if ignored. Still drivable.
Evidence
18 owner reports back this, confidence 55/100.
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
Occasional · Age-related wear. Can destroy the engine if ignored. Still drivable.
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
Occasional · Age-related wear. Does not normally destroy the engine. Still drivable.
Evidence
11 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
Occasional · Age-related wear. Does not normally destroy the engine. Still drivable.
LowIntercooler failure or leak
Intercooler core cracking or pipe seal failure, causing boost loss.
Symptoms
- Power Loss
How often
Very rare · Age-related wear. Does not normally destroy the engine. Still drivable.
- Critical
- High
- Moderate
- Low
Oil pump failurefrom 85k km
High-pressure fuel pump failurefrom 161k km
Water pump failurefrom 128k km
Fuel injector failurefrom 74k km
Variable valve timing solenoid/actuator failurefrom 129k km
Oil leak from seals or gasketsfrom 126k km
Check the car you're looking at
Set the mileage of the car you're looking at. Problems owners say start before it are the ones to ask the seller about; the next ones are what to budget for.
km
2 already past · 3 coming up
Already past: ask for proof
Owners say these start before this mileage. Nothing tells us whether this car had them fixed, so ask, and ask for the invoice.
The next 30k km
Further on High-pressure fuel pump failure
No reliable mileage Piston ringland failure, Rod bearing failure, Head gasket failure, Wastegate / boost actuator failure, Dual-mass flywheel / clutch wear, Intercooler failure or leak
Too few owners said at what mileage these start, so they are not placed above.
Buying checklist
BMW B58 (M340i G20) · Buying checklist
Sources
Updated 12 Sept 2026 · scoring v2.7
Behind this report sit 100 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.