On-Board Diagnostics (California Vehicles)

EGR SYSTEM ON-BOARD DIAGNOSTICS (CALIFORNIA VEHICLES)

The engine controller performs an on-board diagnostic check of the EGR system on all California vehicles with EGR systems. The diagnostic system uses the Electric EGR Transducer (EET) for the system tests.

The diagnostic check activates only during selected engine/driving conditions. When the conditions are met, the engine controller energizes the transducer solenoid to disable the EGR. The controller checks for a change in the oxygen sensor signal. If the air-fuel mixture goes lean, the engine controller will attempt to enrichen the mixture. The engine controller registers a fault if the EGR system has failed or degraded. After registering a fault, the engine controller turns the CHECK ENGINE light on. The CHECK ENGINE light indicates the need for immediate service.

If a malfunction is indicated by the CHECK ENGINE light and a fault code for the EGR system, check for proper operation of the EGR system. Use the System Test, EGR Gas Flow Test and EGR Diagnosis Chart. If the EGR system tests properly, check the system using the DRB II tester.