P0666 - PCM/ECM/TCM Internal Temperature Sensor Range/Performance

The module internal temperature sensor is outside the expected range.

Code Overview

The module internal temperature sensor is outside the expected range.

Common Causes

• Control module, relay, sensor, or actuator fault
• Damaged wiring or connector
• Calibration or power-supply issue

Diagnostic Steps

1. Inspect related connectors, power feeds, and grounds
2. Check supporting scan data and companion codes
3. Confirm the control circuit before replacing the module or actuator

Likely Repairs & Cost Guides

Use test results to confirm the fault before pricing the repair.

Related OBD Codes

Browse the closest code-family pages when the same fault pattern often shows up nearby.

Next Steps

Move from the code to a diagnosis path, then into repair pricing once the fault is confirmed.