OBD-II trouble code
P0667: PCM/ECM/TCM Internal Temperature Sensor Range/Performance
The module's own temperature reading is present and electrically valid but does not agree with the rest of the vehicle. This is the one member of the family you can genuinely diagnose from scan data, and the first question it asks is whether the module is lying or whether it really is hot.
Quick facts
- System
- Powertrain
- Category
- PCM / Electronics
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $100 – $1,600
- DIY difficulty
- Shop recommended
What does P0667 mean?
Range and performance codes are rationality codes. Nothing is shorted, nothing is open, the signal is inside its electrical limits — the module has simply decided the number does not make sense. For P0667 that judgement is made by comparison, because the module has other thermometers on the vehicle to check itself against.
The comparison that matters happens after a long soak. Park a vehicle overnight and every temperature sensor on it converges: the intake air sensor, the coolant sensor, the ambient sensor and the module's own internal sensor should all read within a few degrees of each other and of the air outside. Nothing has run, so nothing is warmer than anything else. At the next key-on the module reads them together, and if its own value sits well away from the others with no explanation, P0667 sets. That is why the code is so often stored on the first start of the day and why it can be impossible to reproduce at a warm shop in the afternoon.
That comparison also gives you the only fork worth making on this code, and it splits the diagnosis in two. **Either the sensor is reporting wrongly, or the module genuinely is at the temperature it claims.** Those are not the same problem and they do not have the same repair.
If the module really is hot after standing overnight, that is a serious and useful finding, because there is only one way electronics get warm with the key off: current is flowing that should not be. A driver stage holding a solenoid energised, a stuck relay feeding a circuit that should be dead, a partially shorted output — any of those keeps a piece of the module dissipating power all night. That fault is often also visible as a parasitic drain and a battery that goes flat over a weekend, and the two complaints are worth connecting when a customer mentions both.
If the module is cold to the touch and cold on the data list from every other sensor's point of view, then the internal sensor or the board around it is drifting, and the module is the repair.
One honest caveat about false alarms. Modules mounted in the engine bay heat-soak badly after shutdown, sometimes climbing well above their running temperature once the airflow stops. A reading taken twenty minutes after a drive proves nothing at all. The comparison is only valid from a genuine cold soak, and taking it at the wrong moment is the most common reason this code gets diagnosed backwards.
Common causes
- Internal temperature sensor drifting out of calibration on the module board
- A module output stage left conducting with the key off, warming the module continuously
- Stuck relay or shorted circuit keeping a driven device energised after shutdown
- High-resistance module ground shifting every internal reference
- Moisture or corrosion on the module board affecting the sensor circuit
- Ageing solder joints on a module that has heat cycled for many years
- A faulty intake air or ambient temperature sensor making the comparison fail from the other side
- Software calibration that has not been updated for a known rationality issue
- A module fitted second-hand from a different climate or specification without correct programming
Symptoms
- Code setting on the first cold start of the day and not returning during the rest of it
- Module internal temperature reading that disagrees with intake air and coolant temperature after an overnight soak
- Check engine light or transmission warning lamp
- Battery going flat over a weekend where a driver stage is conducting with the key off
- The module housing feeling warm to the touch on a vehicle that has not run
- Occasional reduced output or a protective strategy engaging
- No driving symptom whatsoever in many cases
Diagnostic steps
- 1.Take the readings from a genuine cold soak, ideally overnight. A comparison made after a drive is worthless because engine bay modules heat-soak once airflow stops.
- 2.At the first key-on, record module internal temperature, intake air temperature, coolant temperature and ambient temperature together. On a properly soaked vehicle they should all sit within a few degrees of each other.
- 3.Decide the fork before doing anything else: is the module reporting a temperature it is not at, or is it genuinely warm? Touching the housing on a cold vehicle answers this faster than any tool.
- 4.If the module really is warm with the key off, test for a parasitic drain. Something is conducting that should not be, and finding it is the actual repair.
- 5.Pull the fuses feeding the module's outputs one at a time while watching the drain to isolate which circuit is staying alive.
- 6.If the module is cold, verify the other temperature sensors are accurate before blaming the module, since a badly reading intake air or ambient sensor breaks the comparison from the opposite end.
- 7.Measure the module ground and feed under load. A high-resistance ground shifts internal references and produces rationality faults without any component being faulty.
- 8.Check for a manufacturer software update addressing this code before ordering a module, since rationality thresholds are exactly the kind of thing recalibrations change.
- 9.Only after the cold-soak comparison, the drain test and the ground checks all point the same way, quote module replacement and programming.
Repair cost
$100 – $1,600
Diagnosis is $100 to $250, at the higher end when a genuine overnight soak has to be arranged so the comparison is valid. A parasitic drain trace is $120 to $300 and is money well spent when the module is genuinely warm with the key off. Fixing the circuit behind that drain — a stuck relay, a shorted solenoid, a chafed feed — is typically $120 to $600. Ground repair is $80 to $250. Replacing a faulty intake air or ambient temperature sensor that was breaking the comparison is $90 to $250. A software update, where one applies, is $80 to $200. Module replacement with programming is $600 to $1,600.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with control module replacement & programming preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
Leave this one to a qualified shop. It typically involves emissions-critical components, refrigerant handling, or other work that requires manufacturer-grade tooling, training, or certification. DIY attempts often produce a more expensive problem than the original code.