What the P0475 code means
The P0475 means that there is something wrong with your exhaust back pressure valve.
What causes the P0475 code?
There may be more than one cause for the P0475 code. One is a faulty exhaust back pressure valve. Another cause may be that the exhaust back pressure valve is shorted out or open. You may also have a poor electrical connection on your exhaust back pressure valve.
What are the symptoms of the P0475 code?
Your Check Engine light may come on to tell you that your car is having issues with its exhaust valve.
How does a mechanic diagnose the P0475 code?
You can detect problems with either the Exhaust Back Pressure (EBP) Device or the tube between the exhaust manifold and the EBP sensor with an exhaust back pressure step test. This is when the Engine Control Module (ECM) commands and then measures a particular preprogrammed pressure. It then measures time for pressure decay during your engine running test. If the ECM detects an EBP, Intake Air Temperature or Engine Oil Temperature sensor fault, the ECM will disable the exhaust back pressure regulator. This is how you know that you probably have an exhaust pressure control valve malfunction and just what exactly is malfunctioning.
How serious is the P0475 code?
A P0475 code is moderately important. It may not need your immediate attention, but as is true with most car repairs, if you do not take care of the problem quickly, it could cause you additional problems in the future. However, you will still be able to operate your vehicle.
What repairs can fix the P0475 code?
If you have a scan tool, clear the diagnostic trouble codes from memory, and see if the P0475 code returns. If it does not return, then faulty connections are most likely the issue. If the code does return, you will need to test the solenoid and its circuits. Usually there are two wires at the Exhaust Pressure Control Solenoid, and you must first disconnect the harness going to the Exhaust Pressure Control Solenoid. With a Digital Volt OhmMeter, connect one lead of the meter to one of the solenoid terminals. Then connect the other meter lead to the other solenoid terminal. Please note that it should not be open or shorted. Next check the resistance specifications for your particular vehicle. If the solenoid is either shorted or open, you will need to replace the solenoid. Next you will need to determine if you have 12V on your Exhaust Pressure Control Solenoid power supply circuit. Make sure that your ignition is on. If you do not see 12 volts to the solenoid, or if there is 12 volts when the ignition is off, you will need to relay to the solenoid or repair the wiring to the PCM.
In some cases, you may have a bad PCM. But if this is not the case, make sure you have a solid ground at the Exhaust Pressure Control Solenoid. To do this connect a test light to a 12V battery positive (this will be the red terminal) and touch the other end of the test light to the ground circuit that goes to the Exhaust Pressure Control Solenoid circuit ground. If the test light DOES NOT light up, you know you have a problem circuit. If it DOES light up, shake the wiring harness going to each sensor and note if the test light flickers. If it does flicker, you have an intermittent connection. However, if you pass all of these tests and are still receiving a P0475 code, you probably have a failed Exhaust Pressure Control Solenoid.
Additional comments for consideration regarding the P0475 code
Many older vehicles have temporary sensor problems that occur due to prolonged stress on the drivetrain. A P0475 is very difficult to diagnose and repair, and so you might want to consult with a professional before taking this on yourself. While you can still operate your vehicle, you should consider fixing this issue as soon as you can.
Need help with a P0475 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.