Moderate SeveritySafe to drive (short-term)Fuel System
P0171 means the engine's air-fuel mixture is too lean on Bank 1: there's too much air or not enough fuel. The ECU detected that it cannot add enough fuel to maintain the correct 14.7:1 stoichiometric ratio, exceeding its fuel trim correction range.
What does P0171 mean?
P0171 means the engine's air-fuel mixture is too lean on Bank 1: there's too much air or not enough fuel. The ECU detected that it cannot add enough fuel to maintain the correct 14.7:1 stoichiometric ratio, exceeding its fuel trim correction range.
P0171 is a fuel system-related diagnostic trouble code classified as moderate severity. When your vehicle's ECU detects this condition, it stores P0171 and illuminates the check engine light.
What are the symptoms of P0171?
If your vehicle has triggered P0171, you may notice one or more of these symptoms:
lowExhaust leak before O2 sensor (false lean reading)
lowFaulty O2 sensor providing incorrect data to ECU
Is it safe to drive with P0171?
Generally yes, for short-term driving. Short-term driving is generally safe, but a lean condition can cause engine overheating and damage if left unaddressed. Avoid heavy acceleration and fix within a week.
How do you diagnose P0171?
Follow these steps to pinpoint the root cause of P0171:
Check short-term and long-term fuel trims with a scan tool. LTFT above +15% confirms a lean condition
Perform a smoke test or spray brake cleaner around intake manifold gaskets and vacuum hoses. RPM change indicates a leak
Inspect and clean the MAF sensor with dedicated MAF cleaner spray (do not touch the sensor element)
Check fuel pressure at the rail with a gauge. Compare to manufacturer specification
Inspect PCV valve and hoses for cracks or disconnection
Check for exhaust leaks before the upstream O2 sensor that could cause false lean readings
How much does P0171 cost to fix?
Repair costs for P0171 vary depending on the root cause and your vehicle. Here are typical estimates:
Repair
Parts Cost
Labor Cost
Total Estimate
DIY Difficulty
Fix vacuum leak (replace hose or gasket)
€5–€60
€60–€200
€65–€260
Moderate
Clean or replace MAF sensor
€10–€200
€20–€60
€30–€260
Easy
Replace fuel pump
€100–€400
€100–€300
€200–€700
Professional
Clean fuel injectors
€15–€50
€50–€150
€65–€200
Moderate
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
P0171 on specific vehicles
P0171 behaves differently depending on your vehicle. Select your car below for model-specific causes, known issues, and adjusted cost estimates:
P0171 on Toyota Camry
Toyota Camry • 2007–2024
The 2012–2017 Camry 2.5L (2AR-FE) commonly triggers P0171 from intake manifold gasket failures, especially in cold climates. The gasket shrinks with age, creating a vacuum leak that's worst during cold starts. Toyota revised the gasket material in later production runs.
What causes P0171 on a Toyota Camry?
Toyota CamryIntake manifold gasket failure on 2012–2017 2.5L (cold climate accelerates degradation)
Toyota CamryPCV valve hose deterioration on 2AR-FE engine
P0171 on Honda Civic
Honda Civic • 2006–2024
The 1.5L turbo Civic (2016+) is susceptible to P0171 from the wastegate actuator linkage loosening over time, causing boost control issues that the ECU interprets as a lean condition. The R18A in older Civics commonly develops cracked intake manifold runner seals.
What causes P0171 on a Honda Civic?
Honda CivicWastegate actuator linkage loosening on 1.5T (2016+)
Honda CivicCracked intake manifold runner seals on R18A
P0171 repair cost for Honda Civic
Estimated costs for Honda Civic ownersadjusted lower than average due to Honda-specific parts pricing
Repair
Parts Cost
Labor Cost
Total Estimate
DIY Difficulty
Fix vacuum leak (replace hose or gasket)
€5–€54
€54–€180
€59–€234
Moderate
Clean or replace MAF sensor
€9–€180
€18–€54
€27–€234
Easy
Replace fuel pump
€90–€360
€90–€270
€180–€630
Professional
Clean fuel injectors
€14–€45
€45–€135
€59–€180
Moderate
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
P0171 on Volkswagen Golf
Volkswagen Golf • 2005–2024
The PCV valve (also called the crankcase breather or oil separator) is the most common P0171 trigger on VW Golf models. On the EA888 engine, the diaphragm cracks, creating a massive vacuum leak. VW revised the design multiple times. Also check the charge pipe for cracks on turbo models.
What causes P0171 on a Volkswagen Golf?
Volkswagen GolfPCV/oil separator diaphragm failure on EA888 (extremely common)
Volkswagen GolfCharge pipe cracking on TSI/TFSI turbo models
P0171 repair cost for Volkswagen Golf
Estimated costs for Volkswagen Golf ownersadjusted higher than average due to Volkswagen-specific parts pricing
Repair
Parts Cost
Labor Cost
Total Estimate
DIY Difficulty
Fix vacuum leak (replace hose or gasket)
€6–€69
€69–€230
€75–€299
Moderate
Clean or replace MAF sensor
€12–€230
€23–€69
€35–€299
Easy
Replace fuel pump
€115–€460
€115–€345
€230–€805
Professional
Clean fuel injectors
€17–€57
€57–€173
€75–€230
Moderate
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
P0171 on BMW 3 Series
BMW 3 Series • 2006–2024
BMW 3 Series with the N52 engine is notorious for DISA valve and intake manifold flap failures causing P0171. The plastic intake manifold runner flaps break apart and can be ingested by the engine. The N20/N26 4-cylinder turbo engines commonly develop charge pipe cracks at the turbo outlet.
What causes P0171 on a BMW 3 Series?
BMW 3 SeriesDISA valve/intake manifold runner flap failure on N52 (plastic fatigue)
BMW 3 SeriesCharge pipe cracking at turbo outlet on N20/N26
P0171 repair cost for BMW 3 Series
Estimated costs for BMW 3 Series ownersadjusted higher than average due to BMW-specific parts pricing
Repair
Parts Cost
Labor Cost
Total Estimate
DIY Difficulty
Fix vacuum leak (replace hose or gasket)
€7–€84
€84–€280
€91–€364
Moderate
Clean or replace MAF sensor
€14–€280
€28–€84
€42–€364
Easy
Replace fuel pump
€140–€560
€140–€420
€280–€980
Professional
Clean fuel injectors
€21–€70
€70–€210
€91–€280
Moderate
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
Related diagnostic codes
These codes are often seen alongside P0171 or indicate related issues:
It means the air-fuel mixture entering your engine has too much air relative to fuel. The ideal ratio is 14.7 parts air to 1 part fuel. When the ECU can't compensate by adding more fuel (fuel trim maxes out), it triggers P0171.
Can I drive with P0171?
For short distances, yes. But lean conditions cause higher combustion temperatures, which can damage valves, pistons, and the catalytic converter over time. Aim to diagnose and fix within a week.
Why do P0171 and P0174 appear together?
P0171 is Bank 1 lean, P0174 is Bank 2 lean. When both appear simultaneously, the cause is typically something that affects the entire engine, such as a dirty MAF sensor, weak fuel pump, or a large vacuum leak after the MAF sensor.
Can cleaning the MAF sensor fix P0171?
Often, yes. A dirty MAF sensor underreports airflow, causing the ECU to deliver less fuel than needed. Cleaning with dedicated MAF sensor cleaner is a free/cheap fix that resolves P0171 in roughly 30% of cases.
