Engine Dieseling Or Run-On

WARNING: This page is about a different car, the 2002 Saturn LW300 and 2002 Saturn L300. However, it is still accessible from the selected car via links, so may be relevant.

Engine continues to run after key is turned to the Off position, but runs very rough. (If engine runs smooth, check ignition switch.)

Check:
Fuel injectors for fuel leakage.
Perform a fuel system operational test at the pressure test connector. Refer to FUEL SYSTEM PRESSURE TEST (SATURN) . Fuel ignites in intake manifold or in exhaust system, making a loud popping sound.
Check:
- EGR for valve not opening - refer to DTC P0401, P0402, P0404 or P0406 in DIAGNOSTIC TESTS and EGR VALVE (3.0L) in REMOVAL, OVERHAUL & INSTALLATION.
- Intake manifold gaskets for leaks.
- Misfiring, cross firing or cutting out under load.
- Spark plugs. Check for wetness, improper gap, cracks, burned electrodes and heavy deposits.
- Ignition coil connections.
- Ignition system for moisture, dust, cracks, burns, etc.
- ECM and ignition system for faulty grounds.
- Secondary ignition voltage output with service tool SA9199Z tester.
- Engine valve timing and compression.
- Worn or incorrect basic engine parts such as camshaft(s), heads, pistons, rocker arms, lifters, broken or worn valve springs, etc.