P0667 indicates that the engine control module (PCM/ECM) has detected its internal temperature sensor reading is outside the expected range or not performing correctly. This sensor monitors the temperature inside the control module to help the PCM adjust its operation and protect itself from overheating.
The sensor itself is integrated into the PCM and can fail due to age, heat, or manufacturing defect, causing an out-of-range reading.
Corroded, loose, or damaged wiring or connectors at the PCM can affect the sensor signal or power/ground, leading to a range/performance fault.
Low battery voltage, poor ground connections, or charging system issues can cause the PCM to misread its internal sensor.
Occasionally, a software glitch or incorrect calibration can cause a false P0667, though this is less common.
If the sensor circuit or the PCM itself has an internal short or open, the code may set. This is a last-resort cause after all other possibilities are ruled out.
Not necessarily. Many P0667 codes are caused by poor connections, low voltage, or wiring issues. Only replace the PCM after verifying all other possible causes are eliminated. Replacing the PCM without proper diagnosis often does not fix the problem.
In most cases, yes, but the PCM may enter a fail-safe or limp mode that reduces performance. If the PCM overheats or the sensor reading is critical, the vehicle may stall or not start. It is best to diagnose and repair promptly.
It monitors the temperature inside the control module. The PCM uses this data to adjust its internal cooling (if equipped) and to protect itself from thermal damage. An inaccurate reading can affect engine operation and trigger diagnostic trouble codes.
It is less common than many other powertrain codes. It appears more often in vehicles with known PCM issues or after water intrusion, battery problems, or aftermarket modifications. It is not a typical 'first guess' code.