PCM/ECM/TCM Internal Temperature Sensor Range/Performance
Code P0667 indicates the internal temperature sensor of the powertrain control module (PCM), engine control module (ECM), or transmission control module (TCM) is reading outside its normal operating range. This sensor monitors the temperature inside the control module itself to ensure proper operation and prevent damage from overheating or extreme cold.
What You Might Notice
- Check engine light illuminated
- Engine will not start or difficulty starting
- Engine stalling or rough idle
- Improper or delayed transmission shifting
- Transmission warning lamp illuminated
Most Common Causes
- 1
Corroded or damaged connector
The temperature sensor connector may have corrosion, bent pins, or loose connections preventing proper signal transmission to the control module. Moisture and road salt exposure accelerate connector degradation.
- 2
Faulty internal temperature sensor
The temperature sensor inside the PCM/ECM/TCM may be defective or failing, sending incorrect temperature readings or no signal at all to the module's diagnostic circuits.
- 3
Loose or defective control module ground strap
A loose, corroded, or damaged ground connection from the control module prevents proper electrical grounding, causing sensor signal issues and internal temperature sensing failures.
- 4
Faulty PCM, ECM, or TCM
The control module itself may be defective with internal wiring damage, failed sensor circuitry, or component failure requiring module replacement or reprogramming.
How to Diagnose It
- 1
Check Corroded or damaged connector — The temperature sensor connector may have corrosion, bent pins, or loose connections preventing proper signal transmission to the control module. Moisture and road salt exposure accelerate connector degradation.
- 2
Check Faulty internal temperature sensor — The temperature sensor inside the PCM/ECM/TCM may be defective or failing, sending incorrect temperature readings or no signal at all to the module's diagnostic circuits.
- 3
Check Loose or defective control module ground strap — A loose, corroded, or damaged ground connection from the control module prevents proper electrical grounding, causing sensor signal issues and internal temperature sensing failures.
- 4
Check Faulty PCM, ECM, or TCM — The control module itself may be defective with internal wiring damage, failed sensor circuitry, or component failure requiring module replacement or reprogramming.
How to Fix It
- 1
Inspect and clean connector
Locate the PCM/ECM/TCM connector and inspect for corrosion, bent pins, or loose terminals. Clean the connector with electrical contact cleaner and ensure all pins are properly seated and making solid contact.
- 2
Check and repair ground strap
Inspect the ground strap or cable from the control module to the vehicle chassis for corrosion, looseness, or damage. Tighten all ground connections and replace the ground strap if corroded or damaged.
- 3
Inspect wiring harness
Examine the wiring harness connected to the control module for cuts, pinches, exposed conductors, or signs of damage. Repair or replace any damaged sections of wiring, ensuring proper routing away from heat sources.
- 4
Replace control module
If all connections and wiring are intact, the control module itself requires replacement. The internal temperature sensor cannot be replaced separately; the entire PCM, ECM, or TCM must be replaced and programmed with vehicle-specific calibration.
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