How do I fix Ford code 559?

Check the circuit wiring and harness for damage, chafing or a poor splice Test the A/C relay 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

559 A/C on relay circuit failure

Q: What does Ford code 559 mean?

Ford code 559. A/C on relay circuit failure. Applies to 1981-1995 Ford, Lincoln and Mercury EEC-IV vehicles.

Make: Ford (1981-1995)
Category: Body
Severity: Check Engine Light
Applies to: 1981-1995 Ford, Lincoln and Mercury EEC-IV vehicles

How to read it

Code 559 reads as 5 flashes, pause, 5 flashes, pause, 9 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 559 mean?

559. A/C on relay circuit failure. This code sets when your vehicle computer detects a/c on relay circuit failure.

Common causes of 559

Wiring
A/C relay
ECM

How to fix 559

Check the circuit wiring and harness for damage, chafing or a poor splice
Test the A/C relay 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