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EmissionsSeverity Medium: diagnose soon

P0403Exhaust Gas Recirculation "A" Control Circuit

What it means

The ECU sees an electrical fault in the circuit that drives the EGR valve or its control solenoid.

Symptoms

  • Rough idle or stalling
  • Loss of power, sometimes limp mode
  • Black smoke (diesel) or pinging under load (petrol)

Common causes

  • Open or shorted EGR motor/solenoid
  • Wiring or connector fault
  • ECU driver fault

What to check first

  1. Measure the actuator resistance
  2. Check supply and control with the actuator test
  3. Inspect the connector (heat damage is common)
Can I drive with P0403? Usually yes for a short distance, but performance or economy may suffer and the fault can get worse. Diagnose it soon.

Generic OBD-II meaning. Manufacturer-specific meanings and checks can differ; always check the service information for the car.

How to test the parts behind P0403

EGR valveWiring, typical values, multimeter and scope tests

Known engine problems that set P0403

2.0 TDI EA189: EGR valve and EGR coolerVolkswagen, Audi, Skoda, Seat · typically 120,000–220,000 km1.6 TDI EA189: EGR valve stickingVolkswagen, Audi, Skoda, Seat · typically 100,000–200,000 km1.3 Multijet/CDTI: EGR valve cloggingFiat, Opel, Suzuki, Ford, Lancia, Alfa Romeo, Peugeot, Citroën · typically 80,000–180,000 kmToyota 2.0/2.2 D-4D: EGR and intake carbon build-upToyota, Lexus · typically 80,000–180,000 km

Cases with P0403 (0)

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P0403: questions and answers

What does P0403 mean?

P0403: Exhaust Gas Recirculation "A" Control Circuit. The ECU sees an electrical fault in the circuit that drives the EGR valve or its control solenoid.

What are the symptoms of P0403?

Rough idle or stalling. Loss of power, sometimes limp mode. Black smoke (diesel) or pinging under load (petrol).

What causes P0403?

Open or shorted EGR motor/solenoid. Wiring or connector fault. ECU driver fault.

How do you diagnose P0403?

1. Measure the actuator resistance 2. Check supply and control with the actuator test 3. Inspect the connector (heat damage is common)

Can I drive with P0403?

Usually yes for a short distance, but performance or economy may suffer and the fault can get worse. Diagnose it soon.