OBD-I Codes List

Ford 456 Insufficient engine speed decrease during the cruise control KOER test

Make
Ford (1981-1995)
Category
Body
Severity
Check Engine Light

How to read it

Code 456 reads as 4 flashes, pause, 5 flashes, pause, 6 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 How to Read Ford EEC-IV Self-Test Codes walks through the test and what the numbers mean. The general OBD-I guide covers the rest.

What does Ford code 456 mean?

Insufficient engine speed decrease during the cruise control KOER test

Common causes of 456

  • A cruise control servo or cable that cannot release the throttle
  • A throttle linkage that sticks and stays open
  • A blocked vacuum hose that holds the servo applied
  • An internal fault in the PCM cruise control output

How to fix 456

  1. Check the throttle linkage and cruise cable for binding or trapped linkage
  2. Check the vacuum hose at the cruise servo for a blockage that keeps it applied
  3. Test the cruise control servo and replace it only if it fails its own test
  4. Test the PCM last, only after every circuit test has passed
  5. Clear the code, then retest to confirm the fix holds

Source

Qualified source review

Sources and review

Review: qualified. Read the source limits below.

  • Ford trouble codes, Contour, Escort, Mustang, Probe, Taurus and Tempo 1992-1995 (code, description, probable cause)

    archived reference page (troublecodes.net via Wayback Machine)

    Supports: code identity and probable causes

    Independent table on the same archive site with matching code identity and a probable cause column.

    http://web.archive.org/web/20160501223306id_/http://www.troublecodes.net:80/ford/contour-escort-mustang-probe-taurus-tempo-1992-1995/

  • Ford EEC-IV trouble code table: code, fault location, probable cause (Crown Victoria, Mustang, Taurus, Thunderbird 1992-1995)

    reference page (troublecodes.net)

    Supports: per-code probable causes used for the page cause list and test order

    Fetched 2026-09-30. The probable cause column is what the page lists, in source order, with the test order built from it.

    https://www.troublecodes.net/ford/crown-victoria-mustang-cobralxgt-taurus-thunderbird-1992-1995/

Last updated 2026-10-10.

Report a correction for 456. Include your vehicle, the issue and a source if you have one.

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