P0666 - OBD II Trouble Code

Our automotive experts have put together the following information about the P0666 diagnostic trouble code. We've provided the common symptoms that occur when this code is set along with the frequent repairs that address the issues related to the P0666 code.

OBD II Fault Code

• OBD II P0666

OBD-II Code Transmission may not shift properly is defined as a PCM/ECM/TCM Internal Temperature Sensor "A" Circuit

The engine control module (PCM) and/or Transmission Control Module has a temperature sensor built in to prevent the module from overheating. If the control module cannot accurately determine its own temperature, it will set code P0666.

Transmission may not shift properly Symptoms

• Decreased engine performance
• Transmission may not shift properly

Common Problems That Trigger the P0666 Code

• Powertrain Control Module (PCM) failure
• Transmission Control Module (TCM) failure
• Wiring issue