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Code

P0403

Emissions / EGR

EGR circuit malfunction

The EGR valve control circuit has an electrical fault.

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Most likely causes

Faulty EGR valve
Wiring fault
Blown fuse

Symptoms you may notice

Check engine light
Rough idle
Spark knock

Checks to run

Test the EGR valve command
Check wiring and fuse
Inspect for carbon

Tools you may need

Multimeter OBD-II scanner

Always diagnose before replacing. Codes share symptoms; confirm the cause with measurements before buying parts.

Related codes in Emissions / EGR

EGR flow insufficient

EGR sensor A circuit low

EGR flow malfunction

EGR valve range / performance

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