Ford 37 Fuel system indicates rich at idle
How to read it
Code 37 reads as 3 flashes, pause, 7 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 37 mean?
Fuel system indicates rich at idle
Common causes of 37
- Fuel pressure too high
- Leaking or stuck fuel injectors
- Faulty oxygen sensor
- Rich purge from the evaporative system
- Mass air flow measurement high
How to fix 37
- Confirm the code and measure fuel pressure
- Inspect the oxygen sensor signal for a true rich reading
- Test the injectors for leakage or a stuck open condition
- Check the evaporative purge for a rich condition
- Repair or replace a failed part only after the tests
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
Last updated 2026-09-25.
Report a correction for 37. Include your vehicle, the issue and a source if you have one.