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Fault code P0403 means a fault in the EGR control electrical circuit. The ECU detects an electrical anomaly on the EGR valve control: open circuit, short or resistance out of range.

Typical symptoms

• Engine light on
• Rough idle
• Possible limp mode

Most common causes

• Oxidised or loose connector
• Wiring damaged by heat or vibration
• Valve electric motor shorted
• Faulty ECU output stage

How it is checked in diagnosis

• Measuring resistance and supply at the connector
• Actuator test with current draw reading
• Visual check of the wiring in the hot zone

Can you drive with code P0403?

Yes in most cases, but if the car goes into limp mode it must be taken to the workshop.

How MasterTuning helps

We read the real values from the ECU, not just the code: that is the difference between identifying the component responsible and replacing parts by trial and error. After the repair we clear the fault and check that it does not come back. Centres throughout Italy.

Read more: vehicle database · find an installer · what is ECU remapping

Do you have code P0403 on your car? Book a diagnosis at your nearest MasterTuning centre.

Frequently asked questions

What does fault code P0403 mean?

Code P0403 means a fault in the EGR control electrical circuit. The ECU detects an electrical anomaly on the EGR valve control: open circuit, short or resistance out of range.

Can you drive with fault P0403?

Yes in most cases, but if the car goes into limp mode it must be taken to the workshop.

Is clearing code P0403 enough to fix it?

No: if the cause is still present the code comes back after a few kilometres. Clearing should only be done after the repair, with the diagnostic tool.

How much does it cost to fix code P0403?

It depends on the component responsible: the diagnosis is precisely what identifies it with real measurements, avoiding unnecessary replacements that cost far more than the correct repair.