Skip to main content
DTC Troubleshooting: P0666 (0-21)

DTC P0666:
 TCM Internal Temperature Sensor Signal Malfunction
  1. Turn the ignition switch to ON (II).
  1. Clear the DTCs with the HDS.
  1. Turn the ignition switch to LOCK (0).
  1. Turn the ignition switch to ON (II).
  1. Check for DTCs with the HDS.
Is DTC P0666 indicated?
YES -
Update the TCM if it does not have the latest software, or substitute a known-good TCM, then recheck. If the symptom/indication goes away with a known-good TCM, replace the original TCM.
NO -
Intermittent failure, the system is OK at this time.■