What it means
The signals of multiple engine coolant temperature sensors do not correlate within the calibrated tolerance. One sensor drifts or installation offset between channels.
At a glance
- Usually lights the check-engine light
How it works
The engine cooling system may use multiple coolant temperature sensors at different locations, and the control module compares their readings to assess engine temperature. P2D2C sets when those readings do not agree within the calibrated range, which can result from a drifting sensor or crossed wiring channels.
Common causes
Most likely first.
- One sensor characteristic drifted
- Harness incorrectly swapped between channels
Symptoms
- Check engine light on
- Cooling fan runs constantly or not at all
- Cabin heater weak or excessively hot
- Possible long warm-up time or hard cold start
How to diagnose it
- Use a scan tool to save freeze-frame data and compare all available engine coolant temperature readings from a cold start through warm-up.
- Before starting a cold engine, check whether the sensor readings are reasonably close to ambient temperature and to one another.
- Inspect each named sensor's connector and harness routing for corrosion, damage, loose terminals, or swapped channel connections.
- Check the relevant sensor circuits for opens, shorts, or poor connections using the wiring diagram and manufacturer's specifications.
- If wiring checks pass, test the sensors individually against the manufacturer's specification and confirm which reading diverges as the engine warms.
Common fixes
- Repair loose, corroded, or damaged sensor connectors and wiring.
- Correct any crossed coolant sensor channel connections.
- Replace the coolant temperature sensor that fails its specification.
- Clear the code and verify that the readings agree appropriately from cold start to operating temperature.
Can I keep driving?
If the temperature gauge rises abnormally, the engine overheats, or the cooling fan does not operate when needed, stop driving and address the cooling system promptly. Incorrect temperature information can also cause poor heater operation, hard starting, or inappropriate fan control.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.