OBD-I Codes List

Ford 13 Engine RPM below the self test lower limit or idle speed motor did not move

Make
Ford (1981-1995)
Category
Powertrain - Computer and Auxiliary Controls
Severity
Check Engine Light

How to read it

Code 13 reads as 1 flash, pause, 3 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 13 mean?

Engine RPM below the self test lower limit or idle speed motor did not move

Common causes of 13

  • The idle speed motor did not move, so the ECM could not hold idle speed up.
  • A blocked or restricted intake system holds RPM below the lower limit.
  • The throttle linkage is tight or sticking and drags idle speed down.
  • The IAC valve or ISC actuator is stuck closed and cannot raise idle speed.
  • The ECM cannot drive the idle speed motor during the running test.

How to fix 13

  1. Check the idle speed motor and confirm it moves when the ECM commands it.
  2. Check the intake system for a restriction that lowers idle speed.
  3. Check the throttle linkage and its adjustment, and look for a sticking valve.
  4. Test the IAC valve or ISC actuator 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 idle speed stays within the limit.

Source

Source review recorded

Sources and review

Review: checked against the recorded source material.

  • EEC-IV Ford trouble code table (MIL, description, type)

    archived reference page (troublecodes.net via Wayback Machine)

    Supports: code identity and meaning

    Fetched directly. Code row matches the description used in the data file.

    https://web.archive.org/web/20030720231430id_/http://www.troublecodes.net:80/Ford/eec-iv.shtml

  • Ford EEC-IV trouble codes, Crown Victoria, Mustang, Taurus, Thunderbird 1992-1995 (code, fault location, 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 additional probable causes.

    https://web.archive.org/web/20160502051413id_/http://www.troublecodes.net:80/ford/crown-victoria-mustang-cobralxgt-taurus-thunderbird-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 13. Include your vehicle, the issue and a source if you have one.

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