DTC 76: Fuel Injection System

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(s)

1. Clear Self-Learning Data
   
   Start engine and bring to operating temperature. Ensure that 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 30 seconds at 2000 RPM. Stop engine and connect MAF sensor connector.
2. Verify DTC 12 is displayed in Diagnostic Test Mode II. Erase self-diagnostic memory. Verify 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.
3. Check Front HO2S
   
   Turn ignition off. Disconnect front HO2S and ECM wiring harness connectors. Check for continuity between ECM connector terminal No. 46 and HO2S connector terminal "B". See Figure and Figure . Continuity should be present.
4. Check for continuity between ground and the following terminals: ECM connector terminal No. 46 and HO2S connector terminal "B". Continuity should not be present. If continuity is as specified, go to next step. If continuity is not present, repair harness or connectors as necessary.
5. Check Fuel Pressure
   
   Turn ignition off. Relieve fuel pressure. See REMOVE/INSTALL/OVERHAUL article. Install fuel pressure gauge. With ignition on, fuel pressure should be about 34 psi (235 kPa). At idle, fuel pressure should be about 43 psi (294 kPa). 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.