Clearing Codes

1991 Mercury Tracer Base, 4D Sedan, AutomaticSECTION Clearing Codes
WARNING: This page is about a different car, the 1994 Mercury Topaz and 1994 Ford Tempo. However, it is still accessible from the selected car via links, so may be relevant.

To clear codes from PCM memory, start KOEO SELF-TEST. When diagnostic trouble codes appear on test equipment or MIL/CHECK ENGINE light, disconnect jumper wire from Self-Test Input (STI) connector. If using STAR Series Tester, unlatch center button. This procedure erases Continuous Memory Codes from PCM memory. If problem has not been corrected or fault is still present, hard code will immediately be reset in PCM memory.

CAUTION: DO NOT disconnect vehicle battery to clear codes. This will erase stored operating information from Keep-Alive Memory (KAM). To clear KAM, disconnect negative battery terminal for at least 5 minutes.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.