PCM/ECM/TCM Internal Temperature Sensor Circuit High
The P0669 code indicates that the powertrain control module (PCM), engine control module (ECM), or transmission control module (TCM) has detected a high voltage signal from its internal temperature sensor circuit. This sensor monitors the module's internal temperature to prevent overheating. A high reading suggests a short to voltage, a faulty sensor, or an internal module failure. This can lead to incorrect fuel and timing adjustments, potentially causing drivability issues.
01. Most Common Causes
- Short to voltage in the internal temperature sensor circuit
- Faulty internal temperature sensor within the PCM/ECM/TCM
- Internal module failure (PCM/ECM/TCM)
- Corrosion or damaged wiring/connectors to the module
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine performance issues (rough idle, hesitation, stalling)
- Transmission shifting problems (if TCM involved)
- Reduced fuel economy
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for additional codes.
Step 2: Inspect the PCM/ECM/TCM connectors for corrosion, damage, or loose pins.
Step 3: Test the internal temperature sensor circuit for shorts or opens using a multimeter.
Step 4: If wiring and connectors are okay, the module may need replacement or reprogramming.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive for extended periods as the module may overheat, leading to sudden engine or transmission failure. Have it diagnosed promptly.
How much does it cost to fix?▼
Repair costs range from $150 to $500, depending on whether the module needs replacement or just wiring repair. Module replacement can be more expensive.