P0171

System Too Lean Bank 1

Generic code Fuel and Air Metering High severity Hard repair

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iWhat P0171 means

The fault code P0171 indicates that the air/fuel ratio is too lean on Bank 1. This may cause the engine to run poorly or not start at all.

!Possible symptoms

Illuminated check engine light
Poor engine performance
Rough idle or stalling
Reduced engine power or acceleration

?Possible causes

Faulty fuel pump or fuel filter
Leaking or clogged fuel injectors
Faulty Mass Air Flow (MAF) sensor
Vacuum leak in the intake manifold or hoses
Exhaust leak
Faulty Oxygen (O2) sensor
Faulty engine coolant temperature sensor
Low fuel pressure

⚙Related parts

Fuel Injection System: Fuel injection system controls the amount of fuel to be delivered through the fuel injectors. Problems lead to engine misfire, engine stalling

✓Possible solutions

Replace the fuel pump or fuel filter if necessary
Clean or replace the fuel injectors
Replace the Mass Air Flow (MAF) sensor
Check for and repair any vacuum leaks in the intake manifold or hoses
Repair any exhaust leaks
Replace the Oxygen (O2) sensor if necessary
Replace the engine coolant temperature sensor if necessary
Check and increase the fuel pressure if necessary

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P0171 on OBD DashX

Real-world causes, how often this code shows up, and the fix — step by step.

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