P0174 on MINI: How to Diagnose & Fix
System Too Lean (Bank 2)
1 MINI model · 1 documented issue · $400-$800 repair
P0174 on MINI by model: symptoms, diagnosis and fix
All turbocharged direct-injection MINI engines (N14, N18, B46/B48) accumulate carbon deposits on intake valves since fuel is injected directly into the cylinder rather than washing over the valves. This reduces airflow and causes rough running.
Common Symptoms
- Rough idle
- Hesitation on acceleration
- Reduced fuel economy
- Misfire codes
- Loss of power
How to Fix
Walnut blast the intake valves to remove carbon deposits. This should be done every 40-60k miles as preventive maintenance. Install an oil catch can to reduce oil vapor reaching the intake.
P0174 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0174 mean on a MINI?
P0174 stands for "System Too Lean (Bank 2)." P0174 means the engine computer detected that the air-fuel mixture on Bank 2 (the side of the engine with cylinder 2) is running too lean — too much air relative to fuel. The computer monitors this through the oxygen/air-fuel sensors and fuel trims; when it has to add a large amount of extra fuel to compensate and still can't reach the target, it flags the mixture as too lean. A lean condition can cause rough idle, hesitation, or misfires, and over time can raise combustion temperatures. Because it's Bank 2 specific, an unmetered air leak on that bank or a fuel delivery shortfall is typical. On MINI it is documented across 1 model: Cooper S.
What are the most common causes of P0174?
The most common causes of P0174 are: Vacuum or intake air leak (hoses, gaskets, PCV), Dirty or failing mass airflow (MAF) sensor, Weak fuel pump or restricted fuel filter (low fuel pressure), Clogged or underperforming fuel injectors, Leaking intake manifold or throttle body gasket, Faulty or contaminated oxygen / air-fuel sensor, Exhaust leak upstream of the oxygen sensor, Stuck-open EGR valve. The specific cause varies by vehicle.
How much does it cost to fix P0174 on a MINI?
Published repair estimates on MINI range from $400 to $800 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0174 on a different make?
View P0174 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.