What does code P0470 mean?
Code P0470 stands for Exhaust Pressure Sensor Malfunction.
Some vehicles (mainly those with turbocharged engines) have an exhaust pressure sensor (EP). This sensor does exactly what the name implies - it measures exhaust backpressure. This information is sent to the vehicle's computer, the powertrain control module (PCM). Knowing the exhaust back pressure helps the PCM determine control of an emissions device called the exhaust gas recirculation valve (EGR). In some cases, the PCM also uses this information as input for turbocharger control.
On most vehicles, the PCM sends the EP a reference voltage. The EP then varies its internal resistance according to exhaust pressure and the modified voltage signal is read by the PCM. A tube connects the EP sensor to the exhaust manifold.
Code P0470 indicates the PCM has detected a problem with the exhaust pressure sensor (otherwise known as the exhaust back pressure sensor).
P0470 symptoms
- An illuminated check engine light
- Engine performance problems
- Unable to perform regeneration (diesel engines)
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Common causes for P0470
Code P0470 is typically caused by one of the following:
- A faulty EP sensor
- A blocked EP sensor tube
- Exhaust system problems
- Wiring issues
- A problem with PCM
How to diagnose and repair P0470
Perform a preliminary inspection
Sometimes P0470 can pop up intermittently. This is especially true if the code is a history code and not current. Clear the code and see if it returns. If it does, the next step is to perform a visual inspection. A trained eye can check for issues such as broken wires and loose connections. The exhaust system and EP tube should also be inspected closely. If a problem is found, the issue should be repaired and the code cleared. If nothing is discovered, check for technical service bulletins (TSBs). TSBs are recommended diagnostic and repair procedures put out by the vehicle manufacturer. Finding a related TSB can greatly reduce diagnostic time.
Check the circuit
The next step is to verify the EP sensor circuit is intact. This can be done using a digital multimeter (DMM). The EP sensor will have three wires going to it: reference, position sense and ground.
The DMM should measure approximately 5-volts coming to the sensor on the reference wire. To check the ground side of the circuit, the DMM should be switched to the ohmmeter setting. Continuity should be measured between the FP sensor ground wire and ground. There should also be continuity between the FP sensor position sense terminal and the PCM.
