P0403 Code

What is a P0403 Code?

A check engine light can be a troublesome sight for many automobile owners. While the light is essential for alerting you to a potential problem, it lacks information about the issue’s cause or the exact location where it occurs. One of the first steps in resolving the issue is retrieving a diagnostic trouble code (DTC) from your vehicle’s onboard diagnostic (OBD) system using a scan tool.

Thousands of codes exist to pinpoint a problem’s location and provide the information you need to diagnose the issue accurately. In addition, many of these codes can help a car owner or technician determine whether a vehicle is safe to drive. A P0403 DTC often appears when a problem occurs in the exhaust gas recirculation (EGR) system.

What Does a P0403 Code Mean?

One of the primary roles of an EGR system is cycling your vehicle’s exhaust back into the engine’s combustion chamber in the cylinder head. Besides helping reduce cylinder temperatures, this process decreases nitrogen oxide (NOx) emissions from your vehicle. Your vehicle’s powertrain control module (PCM) uses the EGR system’s control circuit to monitor electricity operation and alert you to possible malfunctions.

The P0403 code stands for Exhaust Gas Recirculation A Control Circuit. It means that the EGR system isn’t working the way it should.


Possible Causes of a P0403 Code in a Ford Power Stroke and Other Engines

A P0403 DTC can appear in any vehicle model that uses a PCM, including sport-utility vehicles, vans and trucks with a Ford power stroke engine. Though the code does not identify the particular problem, it offers valuable guidance for diagnosis. 

Some of the common causes of code P0403 include the following:

  • A defective EGR solenoid
  • A bad EGR valve
  • Damaged wiring or connection problems in the EGR solenoid
  • An EGR vacuum line leak
  • Carbon buildup in the EGR passages
  • A problem with the PCM


P0403 Code Symptoms

Like many other DTCs involving your EGR system, a triggered check engine light is one of the first warning signs of a P0403 code. Sometimes, a P0403 code will not affect your vehicle’s drivability until the problem progresses or worsens. Performance issues that can alert you to a problem include:

  • Issues with acceleration
  • Misfiring on startup 
  • The EGR system disabling
  • Engine unstable on idle 
  • Excessive fuel odor coming from the exhaust
  • Stalling when the EGR valve is stuck open
  • Sparking and knocking in the engine


Diagnosing a P0403 Code

During your diagnosis, the first thing to consider is that several specific issues could contribute to your vehicle’s problem. Some diagnostic recommendations for pinpointing the primary cause are:

  • Checking for other codes: Scan your system for other OBD codes. If additional DTCs are present, try to resolve those codes first. If P0403 is the only code present, clear the code and perform a test drive while reading the live data on your scanner.
  • Evaluating the freeze-frame data: Your PCM’s freeze-frame data can help you pinpoint what engine conditions were present when the computer initially triggered the code. This information can be valuable in determining whether the issue is with the valve, the solenoid or somewhere else in the system.
  • Cleaning the EGR valve: Check the valve for soot or carbon buildup that could prevent it from working correctly. Use a valve cleaner and a small-bristled brush to remove the carbon from the gas entry port and the valve’s return tube. After cleaning, clear the check engine light and perform a test drive to see whether the light reactivates.
  • Examining the wiring and connections: If the code persists after cleaning, visually check the wiring’s quality to the EGR temperature sensor and control solenoid. In addition, disconnect and check the EGR valve vacuum control solenoid for an open or short circuit.

Trusting an experienced technician to diagnose your problem is often the best solution for resolving a P0403 issue. A professional diagnosis can pinpoint the exact problem and offer a more accurate estimate for repairs and parts. Many repair shops or service stations will apply the diagnosis price to the final repair cost.  


How Do You Fix Code P0403?

Fixing a P0403 code begins with an accurate diagnosis. Since many P0403 issues result from dirt or faulty wiring, it’s critical to properly inspect and clean your EGR valve before you begin replacing costly components. Some of the most common repairs include:

  • Replacing the shorted or open EGR vacuum solenoid
  • Replacing the defective EGR valve
  • Replacing the corroded connector to the EGR vacuum control solenoid
  • Repairing the shorted connection to the EGR vacuum control solenoid
  • Replacing the leaking vacuum line


Choosing Additives From Hot Shot’s Secret for Your Vehicle

Hot Shot’s Secret offers vehicle owners worldwide a high-quality solution to many potential performance issues, including problems with your EGR system. Our Diesel Extreme and Everyday Diesel Treatment are scientifically proven formulas that can minimize the soot buildup around your EGR valve by improving your engine’s combustion efficiency. 

Browse our full line of additives today to find the best fit for your vehicle’s requirements. Feel free to request additional product information.