P0666 OBD-II: PCM/ECM/TCM Internal Temperature Sensor "A" Circuit
P0666 Severity
Should you fix P0666 yourself?
Identifying an OBD code is just the start of a complete diagnostic routine. Most trouble codes are caused by a sensor reporting a value that is out of range. Just replacing a sensor may not fix underlying issues. Be sure to understand the code, the part or system in your car that the code refers to, and the risks of delaying professional repair.
Proper diagnosis will save you time and money on unnecessary repairs.
Urgent codes indicate immediate action is necessary. These are urgent and significant malfunctions that can cause severe damage to the vehicle or harm the driver and passengers.
What causes OBD-II fault code P0666?
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.
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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
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