P040E

What it means

P040E means the engine control unit has seen an intermittent or erratic signal from EGR temperature sensor 'A' in the exhaust gas recirculation system. The signal jumps, drops out or changes in a way that does not match real temperature change. The exact sensor position and how the fault is judged vary by make and engine.

Symptoms

• Engine warning light on
• Possible reduced performance or limp mode on some models
• Rough running or hesitation at certain loads
• Increased exhaust smoke or emissions
• Other EGR codes stored alongside
• Fault may come and go, often with vibration or heat

Possible causes

• Loose, corroded or damaged connector at the EGR temperature sensorlikely
• Chafed, broken or heat-damaged wiring to the sensor (intermittent open or short)likely
• Failing EGR temperature sensor, often from heat or soot contaminationlikely
• Sooty or sticking EGR valve or cooler causing unusual temperature readingspossible
• Poor reference voltage or ground supply to the sensor circuitpossible
• Fault within the engine control unitrare
• Outdated control unit software where the manufacturer has issued a fix for a known faultrare

How to diagnose

1. Read all stored and pending codes and note freeze frame data, such as engine temperature, load and speed, when the fault set
2. Check for related EGR, exhaust temperature or sensor supply codes and for any manufacturer service bulletins for the model and engine
3. Inspect the sensor connector and wiring for damage, corrosion, moisture, heat damage or rubbing, and wiggle-test them with live data showing
4. Watch the EGR temperature live data while warming the engine and when the EGR operates, looking for spikes, dropouts or readings that do not follow real temperature
5. Check the sensor supply voltage and ground at the connector against the manufacturer's specification
6. Test the sensor resistance or signal against the manufacturer's temperature figures, as values vary by model
7. Inspect the EGR valve, cooler and pipes for heavy soot build-up, leaks or sticking
8. Check whether a control unit software update applies to the vehicle if no physical fault is found

How to fix

• Clean, secure or replace the faulty connector terminals
• Repair or replace damaged wiring, correctly routed and clear of heat sources and sharp edges
• Replace the EGR temperature sensor if it tests out of specification or the signal is erratic
• Clean or replace the EGR valve, cooler or pipes if soot or sticking is affecting the readings
• Repair supply or ground faults found in the circuit
• Update the control unit software only where an outdated version is a documented cause

Can I keep driving?

Nearby codes

• P040DGenericEGR Temperature Sensor A Circuit High
• P040FGenericEGR Temperature Sensor A/B Correlation