DTC P0171: System Too Lean (Bank 1)
P0171 - SYSTEM TOO LEAN (BANK 1)
| Description: |
The adaptive fuel strategy continuously monitors the fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. Refer to
powertrain control software, FUEL TRIM
for more information. |
| Possible Causes: |
Fuel System:
- Damaged or leaking fuel pulse damper
- Fuel filter plugged or dirty
- Damaged or worn fuel pump
- Leaking fuel pump check valve
- Leaking/contaminated fuel injectors
- Low fuel pressure or running out of fuel
- EVAP canister purge valve is leaking when the canister is clean
- Fuel supply line restricted
- Fuel rail pressure sensor bias
Air Induction System:
- Air leaks after the mass air flow (MAF) sensor
- Vacuum leaks
- PCV system is leaking or the valve is stuck open
- Improperly seated engine oil dipstick
- Air induction turbulence due to incorrect air filter
Exhaust System:
- Exhaust leaks in the exhaust manifold gasket or mating gaskets before or near the HO2S
EGR System:
- Vacuum hose disconnected on exhaust gas recirculation (EGR) system module (ESM) applications
- EGR valve tube/gasket leak
- EVR solenoid vacuum leak
Secondary Air Injection:
- Damaged secondary air injection system or a mechanically stuck valve
Air Measurement System:
- Damaged or contaminated MAF sensor
|
| Diagnostic Aids: |
View freeze frame data to determine the operating conditions when the DTC was set. Observe the LONGFT1 and LONGFT2 PIDs. Refer to
ADAPTIVE FUEL DTC DIAGNOSTIC TECHNIQUES
for more information. |
| Application |
Key On Engine Off |
Key On Engine Running |
Continuous Memory |
| All |
- |
- |
GO to Pinpoint Test H
. |