1991 Mercury Cougar LS, 3.8 4FACTORY OEM SERVICE PROCEDURE

Clearing Codes

To clear codes from ECA memory, start KOEO SELF-TEST. When service codes appear on test equipment or 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 ECA memory. If problem has not been corrected, or fault is still present, hard code will immediately be reset in ECA memory.

CAUTION: DO NOT disconnect vehicle battery to clear codes. This will erase stored operating information from the Keep-Alive Memory (KAM). To clear KAM, disconnect negative battery terminal for a minimum of 5 minutes. If KAM has been cleared, drive vehicle 10 miles or more to allow ECA to relearn operating conditions and driving style of vehicle. Driveability may be affected during relearning cycle.
Factory Service Tools

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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.

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