Error code

OBD2 P0403

OBD2P0403
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.

What it means

Exhaust Gas Recirculation Control Circuit.

Severity

moderateCan drive, but symptoms may affect performance and fuel economy.

Summary

P0403 indicates an issue with the Exhaust Gas Recirculation (EGR) control circuit, which is part of the EGR system responsible for reducing harmful emissions by reintroducing exhaust gases into the engine.

Symptoms

  • Check Engine light
  • Rough run or misfire on startup, smoothing out as engine warms up
  • Rough run or misfire when engine hot, yet runs properly on startup
  • Hesitation to accelerate
  • Stalling
  • Fuel smell from exhaust

Common Causes

  • Defective EGR solenoid
  • Lack of electrical signal to the EGR solenoid (short to ground or voltage)
  • EGR valve failure or restriction
  • Vacuum leak affecting EGR operation

Diagnosis

  1. Check for electrical issues with the EGR solenoid (short to ground or voltage)
  2. Inspect vacuum connections and hoses for leaks
  3. Test EGR valve operation using a hand-pump vacuum tester

Fixes

  • Replace defective EGR solenoid
  • Repair or replace faulty wiring and connectors
  • Clean or replace the EGR valve if restricted

FAQ

What is an EGR solenoid?

The EGR solenoid controls the flow of exhaust gases back into the engine to reduce emissions and improve combustion efficiency.

How do I test if my EGR valve is working properly?

Use a hand-pump vacuum tester to apply 16-18 inches of vacuum to the EGR valve port. The diaphragm should move smoothly throughout this range and maintain vacuum.

View source

Not affiliated with OBD2. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.

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