Contaminated or sooty EGR sensor or EGR passages giving a sluggish or stuck reading; Faulty EGR sensor C (position, pressure, temperature or flow, depending on the engine); Damaged wiring, poor connector contact or corrosion in the sensor circuit (signal, reference or earth); EGR valve sticking open or closed so the sensor reading does not match the commanded value; Blocked or leaking EGR pipe, cooler or associated vacuum or pressure lines; Exhaust leak or restriction near the sensor affecting its reading; Fault in the engine control unit or an outdated calibration, where the manufacturer has a known issue.

P044B

EGR Sensor C Circuit Range/Performance.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
4: AreaAuxiliary emission controls
4B: FaultThe specific fault in that area

What it means

P044B is the generic code for an EGR Sensor C circuit range or performance fault. The engine control unit has seen a signal from the third exhaust gas recirculation sensor that is implausible, stuck or does not agree with the commanded EGR operation or other engine data. What 'Sensor C' actually is (for example a position, pressure, temperature or flow sensor) depends on the manufacturer and engine, so check the model-specific information.

Symptoms

Engine warning light on
Rough or unstable idle
Hesitation or poor response under load
Reduced power or engine in limp mode
Increased fuel consumption
Possible smoke or knocking under load

Possible causes

Contaminated or sooty EGR sensor or EGR passages giving a sluggish or stuck readinglikely
Faulty EGR sensor C (position, pressure, temperature or flow, depending on the engine)likely
Damaged wiring, poor connector contact or corrosion in the sensor circuit (signal, reference or earth)likely
EGR valve sticking open or closed so the sensor reading does not match the commanded valuepossible
Blocked or leaking EGR pipe, cooler or associated vacuum or pressure linespossible
Exhaust leak or restriction near the sensor affecting its readingrare
Fault in the engine control unit or an outdated calibration, where the manufacturer has a known issuerare

How to diagnose

Read all stored and pending codes and note freeze frame data (engine load, speed, temperature) to see when the fault set.
Look up which sensor the manufacturer designates as EGR sensor C on this model and engine.
Visually inspect the sensor, its connector and wiring for damage, heat, chafing, corrosion or oil contamination.
Check for exhaust leaks and damaged or loose EGR pipes and any vacuum or pressure lines around the EGR system.
View live data for the sensor and EGR commanded versus actual values at idle and when the EGR is operated, looking for a stuck, slow or erratic signal.
Test the sensor circuit supply, reference, earth and signal for continuity, shorts and voltage drop against the manufacturer's specification.
Remove and inspect the EGR valve and passages for carbon build-up and free movement, following the model-specific procedure.
Check for technical service bulletins or calibration updates for this model if no physical fault is found.

How to fix

Clean carbon deposits from the EGR valve, sensor and passages where the manufacturer permits cleaning.
Replace the faulty EGR sensor C or the EGR valve assembly if the sensor is integrated.
Repair or replace damaged wiring and clean or renew corroded connector terminals.
Replace blocked, leaking or damaged EGR pipes, cooler or lines.
Repair any exhaust leak affecting the sensor reading.
Apply a manufacturer calibration update only if an outdated or faulty calibration is confirmed as the cause.

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but book it in soon as a stuck EGR system can cause poor running, higher emissions and further build-up. If it goes into limp mode or runs very roughly, limit driving until it is checked.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.