P0171 on MINI
System Too Lean (Bank 1)
P0171 on MINI vehicles indicates system too lean (bank 1). Au7o has documented this code across 2 MINI models — most commonly on Cooper S, GP. This code means the engine's computer has detected that the air-fuel mixture on Bank 1 (the side of the engine with cylinder #1) is running too lean — meaning there is too much air relative to fuel. The computer watches the oxygen sensors and has had to add a large amount of extra fuel (long-term fuel trim) to try to compensate, but it has hit its correction limit. A lean condition can cause rough idle, hesitation, reduced power, and over time can run the engine hotter than normal. It usually points to either unmetered air leaking into the engine or not enough fuel being delivered. Typical repair costs on MINI range from $250 to $2,200, depending on the specific model and root cause.
Common Causes of P0171
- •Vacuum or intake air leak (cracked hose, gasket, or PCV system)
- •Dirty or failing mass airflow (MAF) sensor
- •Weak fuel pump or restricted fuel filter
- •Clogged or dirty fuel injectors
- •Faulty or aged upstream oxygen sensor
- •Leaking intake manifold gasket
- •Low fuel pressure or failing fuel pressure regulator
- •Exhaust leak ahead of the oxygen sensor
P0171 on MINI by Model
MINI Cooper S(1 issue)
- Direct Injection Carbon Buildup on Intake Valves2007-2025
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.
MINI GP(2 issues)
- Oil Separator / Crankcase Ventilation Valve Failure Causing Oil Consumption (N14/N18)2007-2014
The N14 and N18 engines fitted to the GP1 and GP2 are well-documented for crankcase ventilation oil separator (CCV) failure, where the plastic separator housing cracks or the internal membrane fails. A failed CCV causes excessive oil to be drawn into the intake manifold and combustion chambers, resulting in visible blue smoke from the exhaust and abnormally high oil consumption between service intervals. MINI issued TSB SI B11 06 11 addressing this concern on N14 and N18 engines.
- High-Pressure Fuel Pump (HPFP) Failure (N14/N18/B48 Turbo DI)2013-2021
MINI GP models with turbo direct-injection engines have documented HPFP failures that can cause long crank/no-start, limp mode, and reduced power. The pump can lose pressure internally or fail electrically, often showing up under hot restarts or heavy load. Owner reports and NHTSA complaints across R56/R60-era MINIs (including GP2’s N18) frequently describe intermittent stalling and repeated fuel-pressure faults.
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View P0171 across all makes →Frequently Asked Questions
What does P0171 mean on MINI?▼
P0171 stands for "System Too Lean (Bank 1)." This code means the engine's computer has detected that the air-fuel mixture on Bank 1 (the side of the engine with cylinder #1) is running too lean — meaning there is too much air relative to fuel. The computer watches the oxygen sensors and has had to add a large amount of extra fuel (long-term fuel trim) to try to compensate, but it has hit its correction limit. A lean condition can cause rough idle, hesitation, reduced power, and over time can run the engine hotter than normal. It usually points to either unmetered air leaking into the engine or not enough fuel being delivered. On MINI specifically, this code is documented across 2 models.
What causes P0171 on MINI vehicles?▼
Common causes on MINI: Vacuum or intake air leak (cracked hose, gasket, or PCV system), Dirty or failing mass airflow (MAF) sensor, Weak fuel pump or restricted fuel filter, Clogged or dirty fuel injectors, Faulty or aged upstream oxygen sensor. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0171 on a MINI?▼
Repair costs on MINI range from $250 to $2,200, depending on the specific model and root cause.
Which MINI models have P0171 documented?▼
Au7o has documented P0171 on 2 MINI models: Cooper S, GP.