637 Transmission fluid temperature sensor circuit above maximum voltage
How to read it
Code 637 reads as 6 flashes, pause, 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 OBD-I code reading guide walks through the paperclip method, code 12, and reading two-digit codes.
What does Ford code 637 mean?
637. Transmission fluid temperature sensor circuit above maximum voltage. This code sets when your vehicle computer detects transmission fluid temperature sensor circuit above maximum voltage.
Common causes of 637
- Faulty transmission fluid temperature sensor
- Open or shorted wiring in the transmission fluid temperature sensor circuit
- Corroded or loose connector at the transmission fluid temperature sensor
- Low or dirty transmission fluid
- Faulty PCM transmission control
How to fix 637
- Confirm the code and check the transmission fluid level and condition
- Inspect the transmission fluid temperature sensor and its wiring for damage and corrosion
- Test the transmission fluid temperature sensor circuit
- Service the fluid before condemning internal parts
- Replace a failed part only after the circuit test fails