Skip the auto shop - Our mechanics make house calls

P0474 OBD-II Trouble Code: Exhaust Pressure Sensor Intermittent

check engine light

P0474 code definition

The P0474 code is stored when the PCM calculates that the voltage reading from the exhaust system back pressure sensor circuit is too low or too high.

What the P0474 code means

In order to control the exhaust back pressure regulator in a diesel or turbocharged engine, the exhaust back pressure sensor supplies a voltage reading to the ECM that indicates the current pressure level. If this data does not match the manufacturer’s specifications, the PCM will store the P0474 code.

What causes the P0474 code?

A clogged back pressure tube, or a faulty exhaust back pressure sensor, are the two most likely causes for the P0474 code to be stored. However, other common causes may include:

What are the symptoms of the P0474 code?

In many cases, the exhaust back pressure regulator will be disabled, in either a closed or open position, when the P0474 code is stored. This may cause reduced engine performance and insufficient turbocharger pressure. The Check Engine Light will be illuminated, and there may be other codes stored in the PCM relating to the turbocharger or the exhaust systems.

How does a mechanic diagnose the P0474 code?

In order to diagnose the P0474 code, a mechanic should first verify the code with an ODB-II scanner. They should then inspect all the electrical components, including wiring and connectors, related to the exhaust back pressure system, and replace or repair any that are damaged, loose, or faulty. After clearing the code from the system, the mechanic should retest the system. If the code returns, the mechanic has successfully diagnosed an issue with the exhaust back pressure system, and can move on to other repairs.

Common mistakes when diagnosing the P0474 code

When diagnosing the underlying cause of the P0474 code, it is common to confuse the issue with a malfunction in the exhaust gas recirculation. The exhaust back pressure tube and the exhaust gas recirculation valve are located in the same area, but both are diagnosed and repaired in different manners.

How serious is the P0474 code?

The P0474 code is an intermediate issue. While the underlying problem causing this code isn’t likely to affect drivability, it may mean that the vehicle will not pass an emissions test until the issue is repaired and the code is cleared.

What repairs can fix the P0474 code?

In order to repair the underlying issue causing the P0474 code, the mechanic will begin with the initial inspection and repair of the electrical components. Once this diagnostic step has been performed, and the issue is revealed to be unrelated, there are other repairs that may be attempted. They include:

  • Clearing or replacing a clogged back pressure tube.
  • Replacing or cleaning a faulty exhaust back pressure sensor.
  • Replacing or repairing a shorted or open exhaust back pressure sensor harness.
  • Manually test individual circuits within the exhaust back pressure system, and replace faulty components.
  • In rare cases, replacing a faulty PCM.

It is important that after each repair is attempted, the code is cleared from the system and the system is retested. This process helps narrow down the underlying cause of the code so that it is not stored again after a repair.

Need help with a P0474 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

P2159 OBD-II Trouble Code: Vehicle Speed Sensor B Range/Performance
Diagnostic Trouble Code (DTC): P2159 P2159 code definition Vehicle Speed Sensor B Range/Performance Related Trouble Codes: P2158: Vehicle Speed Sensor B P2160: Vehicle Speed Sensor B Circuit Low P2161:...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
P0291OBD-II Trouble Code: Cylinder 11 Injector Circuit Low
P0291 code definition When your vehicle’s PCM registers the P0291 code, it means that a voltage reading came from the fuel injector circuit – for cylinder number 11’s fuel injector –...


Related questions

Q: My car just shut off while driving nd wont start bsk up dosent even crank over nothing at all turns on

Without additional detail, this would be tough to diagnose, however the fact that it just shut down out of nowhere as you've described suggests that some kind of sensor or relay may have triggered this. I would suggest having an...

Q: OD2 scanner read trouble code P0101

Your computer may not be able to correctly interpret the data from the mass airflow sensor on your engine causing the P0101 code to keep returning. The manufacturer has a Technical Service Bulletin that came out January 30th of 2015....

Q: Getting 2 then 4 abs codes, brake shutters, speedo dies and engine slowes when Brake and absolutely lights come on,

You definitely want to start by inspecting the front and rear wheel speed sensors; a failure in these circuits will result in several other problems. Begin by connecting a scanner to see if the Powertrain Control Module (PCM) is registering...