Engine Dieseling Or Run-On

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.