DTC P0172 - Fuel Injection System Function-Rich Side
- Check Exhaust/Intake Air Leak - Start engine and allow to idle. Listen for exhaust air leaks before three way catalyst. Listen for intake air leaks after MAF sensor. If any leaks are detected, repair or replace appropriate parts or systems as required. If no leaks are detected, go to next step.
- Check Front HO2S
- Turn ignition off. Disconnect front HO2S harness connector and ECM harness connector. Using an ohmmeter, check for continuity as follows:
- Between ECM harness connector terminal No. 46 and front HO2S harness connector terminal No. 2 (White wire). Continuity should be present.
- Between ground and ECM harness connector terminal No. 46. Continuity should not be present.
- Between ground and front HO2S harness connector terminal No. 2 (White wire). Continuity should not be present.
If continuity is not as specified, repair fault in White wire circuit. If continuity is as specified, go to next step.
- Check Fuel Pressure - Turn ignition to switch to OFF position. Relieve fuel pressure. See N - REMOVAL/INSTALL/OVERHAUL article. Install fuel pressure gauge. With ignition on, fuel pressure should be about 43 psi (3.0 kg/cm2 ). At idle, fuel pressure should be about 34 psi (2.4 kg/cm2 ). If fuel pressure is not as specified, check for fault in fuel pump and related circuitry. If fuel pressure is okay, inspect MAF sensor. See DTC P0100 - MASS AIRFLOW (MAF) SENSOR and go to next step.
- Check Function Of Injectors - Turn ignition on. Using a voltmeter, check voltage between ground and ECM connector terminals No. 102 (White/Black wire), 104 (White/Red wire), 107 (White/Blue wire) and 109 (White/Green wire). See Figure. If battery voltage does not exist, repair fault in wires as required. If battery voltage exists at all terminals, go to next step.
- Turn ignition off. Allow engine to cool. Remove injector assembly, keeping fuel hose and all injectors connected to injector gallery. Disconnect all injector harness connectors. Disconnect ignition coil harness connector. Crank engine for about 3 seconds. If any injector drips fuel, replace faulty injector. If no injectors drip fuel, check ECM pins and terminals for damage. Reconnect ECM harness connector and retest.