P0405 Code

What is a P0405 Code?

A diagnostic trouble code (DTC) alerts you to specific problems with your vehicle. While your check engine light makes you aware of a potential problem, DTCs narrow down the issue and tell you where it’s occurring. Understanding how DTCs work is critical for pinpointing problems in your vehicle and determining whether it is safe to drive. 

When your vehicle’s onboard diagnostic (OBD) system identifies a problem, it activates a warning light and registers a code that explains the issue. A user can retrieve the code by connecting a diagnostic tool or scanner to the OBD port and reading the code on the display screen. Many of today’s vehicle owners encounter a P0405 code when dealing with exhaust gas recirculation (EGR) valve issues. 

What Does a P0405 Code Mean?

DTC P0405 translates to Exhaust Gas Recirculation Sensor A Circuit Low. When your OBD triggers a P0405 code, it typically involves your engine’s EGR system and sensor. The EGR system’s primary role is to keep nitrogen oxide (NOx) emissions at acceptable levels.

The EGR sensor works by detecting the position of the EGR valve and continuously sending signals to your vehicle’s powertrain control module (PCM). The PCM uses these signals to manage the EGR valve’s operation. A P0405 code means that the EGR sensor’s readings show lower-than-usual voltage levels. 


Potential Causes of a Ford P0405 Code

P0405 codes occur on many different makes and models of vehicles that use OBDs, including automobiles with a Ford EGR pressure-feedback system. While the actual code does not pinpoint the cause of the exact problem, it provides direction for a practical diagnosis. One of the primary causes of a P0405 code is a defective EGR valve position sensor.

Other possible causes include:

  • A dirty or bad EGR valve
  • A faulty differential pressure feedback electronic (DPFE) sensor
  • Damaged wires or poor connections to the EGR sensor
  • Grounded or shorted wiring
  • A problem with your vehicle’s PCM, like the need for a software update


Symptoms of a P0405 Code

One of the first ways your PCM notifies you of a possible EGR problem is by activating the check engine light on your dashboard. Besides this warning, there may be no apparent signs of an issue while you operate the vehicle. A P0405 code or EGR issue could be the root cause of your automobile failing an emissions test without obvious operational issues.

Some of the most common symptoms that affect drivability are:


Diagnosing a P0405 Code

Technicians typically begin diagnosing a P0405 code by checking for other DTCs and looking for freeze-frame data captured by the PCM. Additional DTCs can determine if the EGR sensor is in the correct closed position. One of the initial steps a technician will take is clearing the codes and performing a road test to see if they reappear. 

Subsequent steps include:

  • Inspecting the valve: Dirt on your vehicle’s EGR valve could trigger the P0405 code. Clean the dirt and buildup on your EGR valve with a spray cleaner, scrape away the buildup and remove any additional deposits with a brush.
  • Examining the EGR sensor connector: Remove the sensor and check for corrosion in the connecting wire.
  • Checking the circuit voltage: Check the EGR valve’s reference wire with a multimeter while the ignition is on. If the reading does not show the required 5 volts, check if the circuit is shorted or open.
  • Verify the reference voltage: Connect the signal return and sensor reference voltage pins and check the scanner to verify a 100% reading.


Fixing P0405 Code Issues

Since the cost of a new EGR valve can be substantial, it’s critical to run through all the diagnostic steps before replacing the sensor or the entire valve. After ensuring a proper diagnosis, the following repairs may resolve the code issue:

  • Repairing the wiring or connections to the EGR position sensor.
  • Replacing the EGR position sensor.
  • Replacing the DFPE sensor.
  • Replacing the entire EGR valve.
  • Checking the PCM for malfunctions and updating the software if needed.


How Much Does Code P0405 Cost to Fix?

Since various issues can cause a P0405 code to appear, it’s only possible to provide an accurate repair cost by correctly diagnosing and identifying the source. One of the benefits of having a professional diagnose the problem is that the shop will often apply the cost of the diagnosis to the overall repair. Labor and diagnostic fees vary from shop to shop, but you can expect to pay anywhere from $75 to $150 for an accurate diagnosis.

Several ballpark repair prices, including parts and labor, are:

  • EGR position sensor replacement: $100 to $200
  • DPFE sensor replacement: $150 to $300
  • EGR valve replacement: $250 to $500


Choosing Hot Shot’s Secret Additives for Your Vehicle

At Hot Shot’s Secret, we offer an extensive range of fuel additives to improve your vehicle’s performance while helping prevent some of the most common DTC codes and issues. Our Everyday Diesel Treatment and Diesel Extreme are two products that can minimize or entirely stop carbon buildup on the EGR valve in your diesel engine.

Feel free to contact us online with any questions or to obtain additional product information.