412 Cannot control RPM during KOER high RPM check

Make
Ford (1981-1995)
Category
Powertrain - Computer and Auxiliary Controls
Severity
Check Engine Light
Applies to
1981-1995 Ford, Lincoln and Mercury EEC-IV vehicles

How to read it

Code 412 reads as 4 flashes, pause, 1 flash, pause, 2 flashes on the check-engine light. Jumper the self-test input to signal return at the test connector, then run the key on engine off self test and the running self test, counting the check-engine flashes each time.

New to flash codes? The OBD-I code reading guide walks through the paperclip method, code 12, and reading two-digit codes.

What does Ford code 412 mean?

412. Cannot control RPM during KOER high RPM check. This code sets when your vehicle computer detects cannot control rpm during koer high rpm check.

Common causes of 412

How to fix 412

  1. Check the base idle setting and the idle tracking switch
  2. Check the throttle linkage and its adjustment, and look for a sticking valve
  3. Check the circuit wiring for a short to ground
  4. Test the L AC valve and replace it only if it fails its own test
  5. Test the ECM last, only after every circuit test has passed
  6. Clear the code, then retest to confirm the fix holds

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