P0171

The scan tool indicates Diagnostic Trouble Code (DTC) P0171: The fuel system is too lean [Right Bank (Bank 1)].

Description
By monitoring the Long Term Fuel Trim, long term malfunctions in the fuel system will be detected.
If a malfunction has been detected during two consecutive trips, the MIL will come on and DTC P0171, P0172, P0174 and/or P0175 will be stored.

NOTE: If some of the DTCs listed below are stored at the same time as DTC P0171, P0172, P0174 and/or P0175, troubleshoot those DTCs first, then troubleshoot DTC P0171, P0172, P0174 and/or P0175.

P0106*1, P0107, P0108, P1128*2, P1129*2: MAP Sensor
P0135: Right Primary HO2S Heater (Bank 1, Sensor 1)
P0137, P0138: Secondary HO2S (Sensor 2)
P0141: Secondary HO2S Heater (Sensor 2)
P0155: Left Primary HO2S Heater (Bank 2, Sensor 1)
P0401: EGR Flow Insufficient
P1491: EGR Valve Lift Insufficient
P1498: EGR Valve Lift Sensor High Voltage

*1: '96 model only
*2: '97 - 99 models

Possible Cause
- Fuel Pump insufficient flow/pressure
- Fuel Feed Line clogged, leaking
- Fuel Pressure Regulator stuck open
- Fuel Filter clogged
- Fuel Injector clogged, air inclusion
- Gasoline doesn't meet Owner's Manual spec.
- Primary HO2S (Sensor 1) deteriorated
- MAP Sensor range/performance*1
- EGR System insufficient flow
- Exhaust leak