Diagnostic Trouble Code P0403

P0403 “Exhaust Gas Recirculation Control Circuit”


What is code P0403?

Code P0403 stands for “Exhaust Gas Recirculation Control Circuit”. This diagnostic trouble code can show up for reasons related to the exhaust gas recirculation, or “EGR” system on your vehicle. Therefore, it is important to have a qualified technician diagnose the specific problem that caused the code to be stored in your vehicle’s computer.

Get this checked out soon by a CarAdvise shop, where the work will be guaranteed, and one of our expert techs will review any repair orders.

What does code P0403 mean?

If code P0403 shows up on a diagnostic scan of your vehicle, the information indicates to a technician that there is something wrong with the exhaust gas recirculation (EGR) system. 

The EGR system helps your engine to run efficiently, consume less fuel, and emit fewer emissions. It accomplishes this by recycling a small amount of exhaust gas back to the intake system. There, the exhaust gas mixes with the air that enters the combustion chambers. As a result, the chemical composition of the intake air is changed; the amount of oxygen decreases, lowering combustion temperatures so that less of the hazardous nitrogen oxide gas is produced as a byproduct. This allows for a cleaner and more efficient exhaust system. EGR systems are controlled either electronically or by vacuum, depending on your vehicle make, model, and age.

If your vehicle’s ECM (Engine Control Module) senses that the EGR system has malfunctioned due to an electrical short or open in the wiring or other component, it  will store code P0403, and turn on the check engine light.


What causes code P0403?

A number of causes can trigger a code P0403. That is why an accurate diagnosis is essential. Causes of this code include:

Most likely

Other possibilities

  • Faulty Differential EGR Pressure Feedback sensor
  • Excessive vacuum or electrical input to the EGR valve


What symptoms are associated with this code?

Common signs associated with a code P0403 include the following:

  • The check engine light is on or flashing
  • Engine pinging or knocking on acceleration or under a load
  • Reduced fuel economy


How does a technician diagnose code P0403?

If a diagnostic scan of your vehicle indicates a code P0403, a technician will perform tests to pinpoint the problem. These tests include checking for any related trouble codes. The technician will also visually inspect the EGR system and look for any loose or cracked vacuum lines in the engine compartment. A multimeter might be used to run tests on the EGR valve and actuator. If necessary, the technician might need to remove the EGR valve and other related components to clean or inspect. The catalytic converter might also need to be inspected for signs of blockage.


How serious is this code?

In many cases, a code P0403 will not cause any major drivability problems. But in some cases, the problem can lead to a rough engine idle, hesitation, or stalling when you try to accelerate. At the very least, the presence of the check engine light will prevent your vehicle from passing an emissions test. And if the catalytic converter is causing the problem, your engine could lack power or even fail to start.

Get this checked out soon by a CarAdvise shop, where the work will be guaranteed, and one of our expert techs will review any repair orders.


Related Diagnostic Trouble Codes

P0400 Exhaust Gas Recirculation Flow Malfunction

P0401 Exhaust Gas Recirculation Flow Insufficient Detected

P0402 Exhaust Gas Recirculation Flow Excessive Detected

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