What it means
EGR sensor C above upper plausibility — open signal or short to B+. EGR mixes inert exhaust into intake to lower combustion peak temperature — too little raises NOx, too much causes misfires and rough running.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
EGR Sensor C supplies the ECU with feedback about EGR operation. P044D sets when its signal is higher than the expected range, which can result from an open signal line or a short to battery power; the ECU may then disable EGR control.
Common causes
Most likely first.
- Open signal line
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
Symptoms
- Check engine light on
- Pinging or knocking under load
- Power loss and hesitation
- Possible rough idle
- Failed emissions inspection (NOx)
How to diagnose it
- Save freeze-frame data and check for accompanying EGR codes to see when Sensor C’s signal went high.
- Inspect Sensor C’s connector and wiring for a broken signal wire, corroded terminals, or contact with a battery-power source.
- Review Sensor C live data against commanded EGR operation to confirm the high reading persists.
- Test the signal circuit for an open or short to power and verify its connections using the manufacturer's procedure.
- If the wiring is sound, test Sensor C and the ECU input according to the manufacturer's procedure.
Common fixes
- Repair an open Sensor C signal wire.
- Repair wiring shorted to battery power.
- Clean or replace corroded or damaged connector terminals.
- Replace Sensor C if it fails testing after circuit repairs.
Can I keep driving?
Limit heavy loads if the engine knocks, hesitates, or loses power, and arrange diagnosis soon. A disabled or misreported EGR system can increase NOx emissions, while persistent knocking can harm the engine.
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.