The P0669: PCM/ECM/TCM Internal Temperature Sensor Circuit High code indicates that the control module (PCM, ECM, or TCM) has detected a higher-than-expected voltage in the internal temperature sensor circuit. This sensor monitors the control module’s temperature to prevent overheating. High voltage can result from a faulty sensor, wiring issues, or a malfunction within the control module itself.
P0669 – Quick Overview
| Code | Information |
|---|---|
| Meaning | P0669: PCM/ECM/TCM Internal Temperature Sensor Circuit High |
| Is it serious? | Yes, it can lead to incorrect temperature readings and cause improper operation of the control module, possibly leading to overheating. |
| Possible causes | – High voltage in internal temperature sensor circuit in PCM/ECM/TCM – Faulty sensor – Wiring issue |
| How to diagnose? | – Test internal temperature sensor circuit for voltage – Inspect wiring and connectors – Replace PCM/ECM/TCM if necessary |
P0669 Meaning
The P0669 code indicates that the control module (PCM/ECM/TCM) is detecting high voltage in the internal temperature sensor circuit. This sensor helps to monitor the internal temperature of the module. When voltage is too high, the sensor may not provide accurate temperature readings, potentially leading to overheating and improper module operation.
Step-by-step diagnostic guide
| Action | Description | Tools Needed |
|---|---|---|
| Check for Other Codes | Use an OBD-II scanner to check for other related codes, which may provide more context regarding the performance of the control module. | OBD-II Scanner |
| Test the Internal Temperature Sensor Circuit for Voltage | Use a multimeter to measure the voltage in the internal temperature sensor circuit of the PCM/ECM/TCM. Ensure that it is within the manufacturer’s specified range. | Multimeter |
| Inspect Wiring and Connectors | Inspect the wiring and connectors related to the PCM/ECM/TCM for signs of damage, loose connections, or corrosion that could cause a high voltage reading. | Flashlight, Multimeter |
| Test the Internal Temperature Sensor | If possible, test the internal temperature sensor within the control module to ensure it is providing accurate readings. Replace the sensor if necessary. | Diagnostic Tool, Multimeter |
| Replace the PCM/ECM/TCM if Necessary | If the sensor or internal circuit in the PCM/ECM/TCM is faulty and cannot be repaired, replace the entire control module to restore proper function. | Replacement PCM/ECM/TCM, Tools |
| Clear the Code and Test | After making repairs, clear the code using an OBD-II scanner and test the vehicle to ensure the internal temperature sensor and control module are functioning correctly. | OBD-II Scanner, Vehicle Manual |
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Hi, I am Juraj “Yuri” Lukacko. I got frustrated by unhelpful and scammy mechanics, so I decided to learn everything about car diagnostics myself. I test dozens of new car diagnostic tools every month along with learning new strategies to fix and customize cars. About Juraj Lukacko (Yuri)