Skip the auto shop - Our mechanics make house calls

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
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

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
How to Buy Fuel Treatments
Adding a fuel additive to your gas tank when you fill up is one way to clean vital engine parts of deposits, improve the performance of your engine,...
Veteran and Military Driver Laws and Benefits in New Mexico
The state of New Mexico offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch...


Related questions

Q: I scanned my mercedes ML 250 CDI 4Matic W166 with icarsoft MB 2 scanner. Its showing trouble code U144f00. What does it mean ?

The fault being reported is within a Controller Area Network (CAN) function (wiring or device) but the code itself is generic. According to MB, the particular scanner that you are using will have an accompanying description of the code as...

Q: Engine stopped running while driving and will not start again.

Hey there. As you know, this P0340 code indicates the camshaft position sensor is either faulty or not connected properly. The camshaft position sensor monitors the speed of the camshaft providing the ECU with this information. The ECU uses this...

Q: Check engine light turns on and off

Both of these codes are related to the oxygen sensor readings. More often than not, this will be caused by failing oxygen sensors. There could be other issues that can cause these codes, such as an engine misfire, failing catalytic...