Fuel and air

P008F — Coolant Temperature / Fuel Temperature Correlation Fault

Severity: medium Drive with care, to a shop

What P008F means

The PCM compares engine coolant temperature with fuel temperature, especially after the car has sat long enough for both to be close to ambient. If the readings differ too much or don't follow the expected warm-up pattern, it sets P008F. Both values feed fueling, fan control and warm-up strategies, so a bad reading can affect how the engine runs.

Symptoms

  • Check Engine light on
  • Rough idle or hesitation
  • Reduced fuel economy
  • Loss of power
  • Hard starting, cold or hot
  • Cooling fan running at the wrong times
  • Erratic temperature gauge

Possible causes

  1. Faulty engine coolant temperature sensor
  2. Faulty fuel temperature sensor
  3. Wiring or connector problem (corrosion, loose pin, damaged wire) at either sensor
  4. Signal wire shorted to ground or power
  5. Rarely, PCM software issue or internal fault

How to diagnose

  1. Scan for all codes and review freeze frame data, looking for other temperature sensor codes
  2. With a fully cold engine, compare coolant and fuel temperature on a scan tool; both should be near ambient
  3. Warm the engine up and watch whether coolant temperature rises smoothly and fuel temperature responds sensibly
  4. Inspect both sensor connectors and harnesses for corrosion, chafing and moisture
  5. Measure each sensor's resistance and compare with the spec for its temperature
  6. Check the 5 V reference and ground at the connectors with a multimeter
  7. Test signal wire continuity back to the PCM
  8. Look for PCM software updates or bulletins for your vehicle

Common fixes

  • Replace the engine coolant temperature sensor
  • Replace the fuel temperature sensor
  • Repair the wiring or replace a damaged connector
  • Update or reflash the PCM if a software cause is confirmed
  • Clear the code and road test to confirm the repair

Questions and answers

What does P008F mean?

The PCM found that the coolant temperature and fuel temperature readings don't agree as expected. A failed sensor or wiring problem is the most common cause.

Can I drive with P008F?

For a short time, yes, if the engine doesn't overheat and starts normally. Have it diagnosed soon to avoid poor fuel economy and drivability problems.

How do I fix P008F?

Start by inspecting the sensor connectors and wiring, then test the sensors' resistance. Replacing the faulty sensor or repairing the harness usually clears it.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.