P1407 — Volkswagen — EGR Temperature Sensor Signal Too Low
P1407 (Volkswagen): EGR Temperature Sensor Signal Too Low — what it means, the affected system and what to check before replacing parts.
Meaning, symptoms, causes and checks
EGR Temperature Sensor Signal Too Low. Source catalogue definition; confirm applicability using vehicle service information.
Affected system: Powertrain
Symptoms
- Check Engine light illuminated
- Rough engine idle
- Decreased fuel economy
- Poor engine performance under load
- Increased nitrogen oxide (NOx) emissions
Possible causes
- Defective EGR temperature sensor
- Short circuit or open circuit in sensor wiring
- Corroded or loose electrical connector
- Heavy carbon buildup on sensor tip
- Faulty Engine Control Unit (ECU)
What to check
- Inspect the electrical connector at the EGR temperature sensor for corrosion or bent pins
- Measure the resistance of the sensor using a multimeter and compare to manufacturer specifications
- Check the wiring harness for continuity and signs of heat damage or short circuits
- Verify the sensor signal voltage at the ECU terminal using a scan tool
- Clean or replace the sensor if carbon deposits are preventing accurate temperature readings