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P2038 OBD-II Trouble Code: Reductant Inj Air Press Sensor Circ Range/Performance

Check Engine Light

The P2038 code is a general OBD-II diagnostic trouble code that points to a fault with the reductant injection air pressure sensor “A” circuit range / performance.

What the P2038 code means

The reductant injection system adds air or fluid to the exhaust system to aid in the burning of emissions gasses. The air pressure sensor is used to monitor the pressure of the exhaust.

When out of range sensor performance is detected the P2038 code is set. This causes the Check Engine Light to be displayed on the dashboard and a failsafe mode enabled. The failsafe mode is used to protect the vehicle from further damage and will remain in effect until the sensor falls within range or the fault is resolved.

What causes the P2038 code?

The most likely causes of the P2038 code are:

  • An open or short in the wiring harness
  • Exhaust pressure sensor failure
  • Exhaust leak
  • Poor electrical connection

What are the symptoms of the P2038 code?

In most cases, the P2038 code will not have any symptoms other than the Check Engine Light on the dashboard. The vehicle may suffer a lower than normal fuel mileage and the exhaust emissions may be higher.

How does a mechanic diagnose the P2038 code?

A mechanic will begin by hooking up a scan tool and checking for any codes stored in the ECU. Any codes found, as well as their associated freeze frame data, will be noted. All codes will be cleared and a road test will be performed under similar conditions as the freeze frame data.

A visual inspection will be done looking for any obviously damaged or broken components. Next, the scan tool will be used to check the EGT sensor readings and the exhaust gas pressure readings. Once the exhaust gas temperature is checked, a multimeter will be used to check for the proper voltage at the pressure sensor. Finally, the exhaust system will be checked for any leaks present.

Common mistakes when diagnosing the P2038 code

The most common mistake is overlooking an exhaust leak as the cause of P2038, and looking at more extensive issues. Step-by-step diagnosis is key to accurately fixing the P2038 code.

How serious is the P2038 code?

The P2038 code will not prevent the vehicle from being driven in any way once the code is triggered. With any code this should be repaired as soon as possible for normal vehicle operation.

What repairs can fix the P2038 code?

Common repairs for the P2038 code are:

Additional comments for consideration regarding the P2038 code

Looking for an exhaust leak can be easy if the right steps are taken. The first way is to check for any black sooty stains on the exhaust. This is a clear indication of unburned fuel particles exiting the exhaust in the form of a leak. Another way to check is placing your hand close to the exhaust to feel for any air exiting the exhaust while the engine is running. Caution should be taken when performing this method as the exhaust is very hot and will easily burn your hands.

Need help with a P2038 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

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