Confirmation Procedure
- Start the engine. Hold the engine speed at 3000 RPM without load (in P or N) until the radiator fan comes on, then let it idle.
- Test-drive the vehicle under these conditions:
- HDS [ ECT Sensor 1 ] above 158 deg.F (70 deg.C)
- Transmission in D
- Vehicle speed between 45 - 75 mph (70 - 120 km/h) for 5 minutes or more with cruise control set
- Vehicle speed between 55 - 75 mph (90 - 120 km/h) for 10 seconds, then decelerate (with the throttle fully closed). Repeat this three or more times
- Maintain the vehicle speed at 55 mph (90 km/h) for 4 minutes or more with cruise control set
- Monitor the [ OBD STATUS ] for DTC P0420.