P0667 — PCM/ECM/TCM Internal Temperature Sensor “A” #

Note: The code label may vary depending on the vehicle manufacturer.

• P0667 — PCM Internal Temperature Sensor “A” Circuit (Ford, GM)
• P0667 — ECM Internal Temperature Sensor “A” Circuit (Toyota, Honda)
• P0667 — TCM Internal Temperature Sensor “A” Circuit (Nissan, Chrysler)

Summary of DTC P0667 #

When your scan tool displays P0667, it means the vehicle’s main control unit—whether the Powertrain Control Module (PCM), Engine Control Module (ECM), or Transmission Control Module (TCM)—has detected a problem with its own internal temperature sensor “A” circuit. This sensor monitors the temperature inside the controller to prevent overheating and ensure proper operation. A fault in this circuit can lead to incorrect temperature readings, which may force the module into a protective mode or cause drivability issues. Since these modules are vital for engine and transmission management, addressing this code promptly is crucial. The root cause can range from electrical faults to internal module failures.

Common Symptoms for DTC P0667 #

A malfunction with the internal temperature sensor “A” often produces subtle but noticeable symptoms. Sometimes, you might not feel any difference while driving; other times, the effects can be more pronounced if the module enters fail-safe mode to protect itself. Watch for these typical signs:

• Check Engine Light (CEL) or Malfunction Indicator Lamp (MIL) illuminated
• Erratic engine or transmission behavior (unexpected shifting, hesitation, or rough idle)
• Reduced engine or transmission performance (limp mode)
• Unable to complete readiness monitors or emission tests
• Unexpected cooling fan operation

Probable Causes of Code P0667 #

The most common causes for a P0667 DTC relate to the sensor circuit or the module itself. Here’s what usually triggers this code, listed from most to least likely:

1. Internal failure of the temperature sensor within the PCM/ECM/TCM
2. Electrical issue in the sensor circuit (open, short to ground, or short to power)
3. Corrosion, water ingress, or connector damage at the module harness
4. Faulty or failing PCM/ECM/TCM due to overheating or internal electronic component failure
5. Software or calibration issue (rare, but possible with certain OEM updates)

Step-by-Step Diagnostic for P0667 #

Diagnosing P0667 requires patience and attention to detail, since the fault lies within the module or its immediate electrical environment. Here’s a methodical approach:

• 1. Verify the code: Use a scan tool to confirm P0667 is present and check for related codes (such as communication or module power faults).
• 2. Inspect the module and harness: Visually examine the PCM/ECM/TCM and its connectors for corrosion, water damage, bent pins, or loose connections.
• 3. Check power and ground: With a multimeter, ensure the module is receiving correct power supply and ground.
• 4. Check for technical service bulletins (TSBs): Look up OEM TSBs related to P0667 for known faults or software updates.
• 5. Evaluate module temperature: If scan data is available, compare reported internal temperature with ambient temperature; a large discrepancy may indicate sensor failure.
• 6. Perform a wiggle test: Gently move the wiring harness while monitoring live data for sudden jumps or drops.
• 7. If all external checks pass, suspect internal sensor or module failure—replacement or reprogramming may be required.

Possible Repairs for P0667 #

Once you’ve isolated the cause, here are the most effective repairs for P0667:

• Repair or replace damaged connectors or wiring at the module
• Clean and reseat module connectors if corrosion or moisture is detected
• Repair or replace module ground or power supply circuits
• Replace the PCM/ECM/TCM if internal sensor is confirmed faulty (module replacement may require programming by the OEM or a qualified technician)
• Update or reflash module software if an OEM TSB addresses this issue

Is It Safe to Drive with Code P0667? #

Driving with a P0667 code is not recommended for extended periods. While the vehicle may operate normally in some cases, the risk of module overheating or entering limp mode is real. The control module may also limit engine or transmission performance to protect itself, which can compromise safety and reliability. If the engine or transmission behavior becomes erratic, discontinue driving and seek professional diagnosis immediately.

Vehicles Most Commonly Affected by P0667 #

While P0667 can appear on a wide range of vehicles, it is most frequently reported on certain models, especially those with high mileage or exposure to moisture. Based on field data and repair records, the following are more likely to be affected:

• Ford F-Series (F-150, F-250, F-350)
• Chevrolet Silverado, GMC Sierra
• Toyota Camry, Corolla
• Honda Accord, Civic
• Nissan Altima, Sentra
• Chrysler 200, 300, Pacifica

Common Mistakes & Best Practices with P0667 #

Misdiagnosing P0667 is easy if you overlook the details or skip steps. To avoid common pitfalls and ensure a thorough repair, keep these tips in mind:

• Assuming the module needs immediate replacement without checking power, ground, and connector integrity
• Neglecting to inspect for water intrusion or corrosion at the module location
• Overlooking relevant TSBs or OEM software updates
• Forgetting to clear the code and verify repair effectiveness after addressing the issue
• Not using a scan tool capable of reading live module temperature data

Express FAQ for P0667 #

Still have questions? Here are fast answers to the most common concerns about P0667:

• Q: Can I clear the code and keep driving?
  A: Clearing the code may temporarily turn off the light, but the underlying problem remains. The code will likely return until the root cause is fixed.
• Q: Is module replacement always required for P0667?
  A: Not always. Sometimes, cleaning connectors or repairing wiring solves the issue. Only replace the module if it’s confirmed to be internally faulty.