P044C: EGR Sensor C Circuit Low

What it means

EGR sensor C below lower plausibility — short to ground. 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 feeds the ECU information about EGR operation so it can control exhaust-gas recirculation. P044C means Sensor C’s signal is below the expected range, commonly because the signal is shorted to ground or its circuit has excessive resistance; the ECU may disable EGR control.

Common causes

Most likely first.

1. Short to ground
2. Connector pins corroded - high contact resistance
3. Harness chafing through insulation

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

1. Record freeze-frame data and check for related EGR codes to determine when Sensor C’s signal went low.
2. Inspect Sensor C’s connector and harness for corrosion, chafing, or a wire contacting ground.
3. Check Sensor C live data and compare it with commanded EGR operation to confirm the low reading is present.
4. Test the signal wire for a short to ground and check connector terminals for corrosion or high resistance using the manufacturer's procedure.
5. If the circuit is sound, test Sensor C and the ECU input according to the manufacturer's procedure.

Common fixes

• Repair a signal wire shorted to ground.
• Clean or repair corroded Sensor C terminals.
• Replace damaged wiring or a connector with poor contact.
• Replace Sensor C if it fails testing after circuit repairs.

Can I keep driving?

Avoid heavy loads if the engine pings, hesitates, or loses power; low EGR feedback can allow combustion temperatures and NOx emissions to rise. Continued knocking can damage the engine.