556 Fuel pump relay primary circuit failure
How to read it
Code 556 reads as 5 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 OBD-I code reading guide walks through the paperclip method, code 12, and reading two-digit codes.
What does Ford code 556 mean?
556. Fuel pump relay primary circuit failure. This code sets when your vehicle computer detects fuel pump relay primary circuit failure.
Common causes of 556
- IFS switch
- Wiring
- Fuel pump relay
- Constant control relay module
- ECM
How to fix 556
- Test the IFS switch and replace it only if it fails its own test
- Check the circuit wiring and harness for damage, chafing or a poor splice
- Check the fuel filter and the fuel pump delivery
- Test the constant control relay module and replace it only if it fails its own test
- Test the ECM last, only after every circuit test has passed
- Clear the code, then retest to confirm the fix holds