P0404

Exhaust Gas Recirculation (EGR) "A" Control Circuit Range/Performance

Car Fault Codes Emissions & exhaust

Can you still drive? With care, short trips only

Who can fix it? Needs a workshop

Typical repair time 30 minutes – 3 hours

Typical cost SAR 150 to 1,800

What it means

The engine computer has detected that the actual EGR valve position does not match the position it commanded, or that the valve moves too slowly. This is usually caused by carbon restricting the valve or a faulty position sensor.

Symptoms4

Check engine light on.
Rough idle if the valve sticks open.
Light knocking under load if the valve stays closed.
Occasional stalling at idle.

Possible causes5

Carbon buildup restricting EGR valve movement.
Faulty valve position sensor, often built into the valve.
Weak or worn electric motor inside the valve.
High resistance in the wiring or connector.
Weak vacuum supply on vacuum-operated systems.

How to diagnose5

Compare the commanded and actual valve position on a scan tool while operating the valve.
Remove the valve and check its movement and carbon buildup.
Check the reference voltage, ground and position sensor signal at the connector.
Inspect the connector for corrosion or looseness.
Check the vacuum supply to the valve if it is vacuum operated.

How to fix5

Repair the connector or wiring if a fault is found.
Clean carbon from the valve and its passages.
Run the valve position relearn with a scan tool if the vehicle requires it.
Replace the EGR valve if it stays slow or its position sensor has failed.
Clear the codes and confirm commanded and actual positions match.

Repair cost

0–500

500–2,000

2,000–5,000

5,000+

In Saudi riyals; the highlighted part is the expected range for this fault.

The cost is low for a connector repair or carbon cleaning, and reaches the upper end when the electronic valve with its built-in sensor is replaced.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions

What is the difference between P0403 and P0404?

P0403 points to an electrical fault such as an open or short. P0404 means the circuit works electrically, but the valve movement or position does not match what the computer commands.

Will cleaning the valve help?

Often yes, if carbon is restricting it. If the built-in position sensor has failed, the valve must be replaced.

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This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.

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