DTC P0171: Fuel Trim System Lean
- Check fuel pressure. See BASIC TESTING - 1.8L article. If fuel pressure is within specifications, go to next step. If fuel pressure is not as specified, repair as necessary. Retest system.
- Check fuel injectors. See CIRCUIT TESTS in BASIC TESTING - 1.8L article. If problem exists, repair as necessary. Retest system. If fuel injectors are okay, go to next step.
- Check fuel lever sensor following procedures in DTC P0461 . If problem exists, repair as necessary. Retest system. If fuel level sensor is okay, go to next step.
- Check MAF sensor circuit performance following procedures in DTC P0101 . If problem exists, repair as necessary. Retest system. If MAF sensor circuit is okay, go to next step.
- Check ECT sensor circuit performance following procedures in DTC P0125 . If problem exists, repair as necessary. Retest system. If ECT sensor circuit is okay, go to next step.
- Check HO2S No. 1 sensor circuit performance following procedures in DTC P0131 , DTC P0132 and DTC P0134. If problem exists, repair as necessary. If HO2S No. 1 sensor circuit is okay, replace PCM. Retest system.