What it means
Same as P23CD with the feedback voltage above the plausible range. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
How it works
The fuel heater control module sends heater-status feedback to the engine control module. P23D0 sets when the feedback signal rises above its plausible range, often because the feedback wire contacts a power supply.
Common causes
Most likely first.
- Feedback line shorted to supply
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
Symptoms
- Check engine light
- Fuel or powertrain warning light, if equipped
- Hard starting or rough running in cold weather
- Reduced engine performance in cold conditions
How to diagnose it
- Record freeze-frame data and check the heater command and feedback reading while the fault is active.
- Inspect the feedback harness for pinched insulation or contact with a powered wire or terminal.
- Check both module connectors for moisture, corrosion, loose pins, or terminals pushed back into the connector body.
- Compare the live feedback signal with changes in the heater command to confirm whether it stays high.
- Test the feedback wire for an unintended connection to a supply circuit, following the manufacturer's wiring information.
Common fixes
- Repair feedback wiring where it is pinched against a supply wire.
- Clean or replace corroded, wet, or damaged connector terminals.
- Replace a damaged harness section that allows the feedback wire to contact a powered circuit.
- Replace the fuel heater control module if the wiring tests correctly and the module output is confirmed faulty.
Can I keep driving?
The engine control module may not be able to confirm fuel heater operation, which can lead to hard starting or reduced performance in cold weather. Driving in mild conditions may be possible if the engine runs normally, but avoid depending on the vehicle in freezing conditions until diagnosed.
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.