DTC 76/P0170 - Fuel Injection System

NOTE: O2S is not equipped with heating element on M/T vehicles except vehicles with California emissions.

This DTC identifies a lean or rich fuel condition resulting in adaptive fuel strategy adjusting fuel system to compensate. Possible causes for this fault are as follows:

Intake air leak
Lack of fuel
Incorrect fuel pressure
Exhaust gas leak
Fault in fuel injector(s)
Faulty front HO2S
Faulty MAF sensor

Clear Self-Learning Data

Start engine and bring to operating temperature. Ensure no leaks are present in exhaust or intake air system. Stop engine and disconnect Mass Airflow (MAF) sensor connector. Start engine and run for at least 3 seconds at 2000 RPM. Stop engine and connect MAF sensor connector. Ensure DTC 12 is displayed in Diagnostic Test Mode II. Erase self-diagnostic memory. Ensure DTC 55 is displayed in Diagnostic Test Mode II. Start engine and allow to idle for 10 minutes. If DTC 76 is present, go to next step. If DTC 76 is not present, fault is intermittent and cannot be duplicated at this time.

Check Front HO2S

Turn ignition off. Disconnect front HO2S and ECM harness connectors. See Figure and Figure . On all models with HO2S, check harness continuity between ECM connector terminal No. 46 and HO2S connector terminal No. 2 (White wire). On all models without HO2S, check harness continuity between ECM connector terminal No. 46 and O2S connector terminal No. 1 (White wire). See Figure. Continuity should be present. On all models, check for continuity between ECM connector terminal No. 46 and ground, or between HO2S connector terminal White wire and ground. Continuity should not be present. If continuity is as specified, go to next step. If continuity is not as specified, repair harness or connectors as necessary.

Check Fuel Pressure

Turn ignition off. Relieve fuel pressure. See procedures in the REMOVE/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 okay, check for fault in fuel injector(s). If fuel pressure is not as specified, check for fault in fuel pump and related circuitry.