Fault-Code Library · EGR
P0403: Exhaust-gas recirculation control circuit malfunction
The ECU detects an electrical fault in the EGR valve or its control circuit.
Common symptoms
- •Engine warning light
- •Reduced power
- •Rough running
- •Emissions fault
Likely causes
- •Failed EGR actuator
- •Connector contamination
- •Damaged harness
- •Control-module driver fault
First checks
- •Inspect the EGR connector and wiring
- •Check power, ground, and command
- •Run an actuator test while monitoring position
Important
Carbon restriction and an electrical circuit fault are different problems; confirm both mechanical movement and circuit integrity.
A fault code identifies a detected condition, not a failed part. Confirm manufacturer-specific subcodes and live data.
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