DTC P0171: Fuel System Lean, Or P0172: Fuel System Rich (Esteem 1.8L)
NOTE:
If any DTCs besides DTC P0171 and P0172 are set, diagnose those DTCs first.
- Check intake and exhaust system for leakage. Repair as necessary. If intake and exhaust system are okay, go to next step.
- Check fuel pressure. Go to FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article. Fuel pressure should be 38-44 psi (2.7-3.1 kg/cm2 ) with key on and engine off, and 31.3-36.9 psi (2.2-2.6 kg/cm2 ) with engine running at idle. If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, go to CIRCUIT TEST B-3: FUEL PRESSURE INSPECTION under SYSTEM TESTS in BASIC DIAGNOSTIC PROCEDURES article.
- Inspect fuel injectors and fuel system circuit. Go to CIRCUIT TEST B-1: FUEL INJECTOR CIRCUIT INSPECTION under SYSTEM TESTS in BASIC DIAGNOSTIC PROCEDURES article. Repair as necessary. Retest system. If fuel system is okay, go to next step.
- Turn ignition off. Connect scan tool. Turn ignition on. Check fuel level on scan tool. Add one gallon (3.7L) of fuel to tank. Recheck fuel level. If fuel level increases on scan tool, fuel level sensor is okay. If fuel level does not increase, go to DTC P0461: FUEL LEVEL SENSOR (GAUGE) CIRCUIT PERFORMANCE PROBLEM (ESTEEM 1.8L) .
- Check MAF sensor performance. Go to DTC P0101: MASS AIRFLOW (MAF) SENSOR CIRCUIT PERFORMANCE (ESTEEM 1.8L) . If MAF sensor performance is okay, go to next step.
- Check ECT sensor performance. Go to ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article. Repair as necessary. If ECT sensor performance is okay, go to next step.
- Check HO2S-1 performance. Go to DTC P0131: HEATED OXYGEN SENSOR (HO2S) NO. 1 CIRCUIT LOW INPUT, OR DTC P0132: HEATED OXYGEN SENSOR (HO2S) NO. 1 CIRCUIT HIGH INPUT (ESTEEM 1.8L) . Replace HO2S-1 as necessary. If HO2S-1 is okay, replace PCM.