AutoDiag

P0404

Exhaust Gas Recirculation "A" Control Circuit Range/Performance

Moderate· Fix soonIntermediatePowertrainGeneric, all makes

What it means

The EGR valve is not moving to the position the ECU commands. Usually it is sticking with carbon.

Is it safe to drive?

Usually drivable. If the valve sticks open, the engine may stall at idle.

Symptoms

  • Check engine light on
  • Rough idle
  • Hesitation

Probable causes

Most likely first

  1. 1Carbon on the EGR valve
  2. 2Failing EGR valve motor
  3. 3Faulty position sensor

How to diagnose it

Work through these in order before buying parts

  1. 1Record the code and its freeze frame data (speed, load, temperature when it set), then clear it and see if it comes back.
  2. 2Compare commanded and actual EGR position on live data.
  3. 3Remove and inspect the valve.
  4. 4Check for technical service bulletins (TSBs) or software updates for your make and model; some codes have known factory fixes.

Common fixes

  • Clean or replace the EGR valve

This information is general guidance for all makes. Exact causes, specifications and procedures vary by vehicle, so confirm with your service manual or a qualified mechanic before replacing parts.