P2037 OBD-II Trouble Code: Reductant Injection Air Press Sensor Circuit

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P2037 trouble code definition

The P2037 diagnostic trouble code is an indication that there is an issue with the reductant injector air pressure sensor circuit.

Related trouble codes:

P2038 OBD-II Trouble Code (DTC): Reductant Injection Air Press Sensor Circuit Range/Performance
P2039 OBD-II Trouble Code (DTC): Reductant Injection Air Press Sensor Circuit Low Input = P2040 OBD-II Trouble Code (DTC): Reductant Injection Air Press Sensor Circuit High Input
P2041 OBD-II Trouble Code (DTC): Reductant Injection Air Press Sensor Circuit Intermittent

What the P2037 code means

The reductant injector air pressure sensor sends voltage reading information to the powertrain control module (PCM), using sensors in the exhaust system. The PCM interprets these readings as pressure or exhaust gas temperature. When the voltage readings are higher or lower than that of the predetermined manufacturer specifications, the Check Engine Light will come on and the PCM will store the P2037 diagnostic trouble code.

What causes the P2037 code?

  • Wiring that is loose, broken, or corroded
  • Terminals that are loose, broken, or corroded
  • Connectors that are loose, broken, or corroded
  • Faulty reductant injection air pressure sensor
  • Internal short in the reductant injection pressure sensor circuit
  • Short to ground in the reductant injection pressure sensor circuit
  • Short to ground in the exhaust gas temperature sensor (EGTS)
  • A decrease in back pressure caused by a high performance aftermarket exhaust system
  • A large exhaust leak that is located before the placement of the reductant injection air pressure sensor

What are the symptoms of the P2037 code?

  • Check Engine Light is on
  • No visible symptoms present
  • Black smoke bellowing from the tailpipe during acceleration

How does a mechanic diagnose the P2037 code?

  • Visually inspect the wiring for damage, frays, or wires that have melted.

  • Visually inspect the connector for damage, frays, or corrosion.

  • Repair or replace damaged wiring and/or connectors, as necessary.

  • Retest the system to make sure that the wiring and connectors are in working order.

  • Use an OBD-II scanner to collect all diagnostic trouble codes that been stored by to the powertrain control module, as well as freeze frame data.

  • Clear the trouble code and complete a test drive.

  • If the code does not return after you have completed the test drive, this is an indication that there may be an intermittent condition. Intermittent conditions are often difficult to diagnose, and may require time to get worse before they can be diagnosed properly.

  • Inspect the circuity of the exhaust gas temperature sensor (EGTS)/exhaust gas pressure sensor (EGPS) near where the hot exhaust components are close to wiring and connectors.

  • Repair or replace damaged circuitry, as necessary.

  • Retest the system to make sure that the circuitry of the exhaust gas temperature sensor and pressure sensor are working properly.

  • Check the resistance of the EGTS/EGPS. The resistance specification are determined by the manufacturer, but are typically 150 ohms. A resistance reading of below 50 ohms indicates that the sensor needs to be replaced.

  • Use a heating component to test the resistance with the volt/ohmmeter. The resistance level should decrease when the heating component is added and it should increase as the sensor cools. If this does not happen, this is an indication that the EGTS/(EGPS) needs to be replaced.

  • Check the voltage of the EGTS)/EGPS, at the electrical connector. The voltage reading should be at 5-volts.

  • If the voltage reading of the EGTS/EGPS is not at 5-volts, check the continuity between the PCM and the signal wire.

  • If there is continuity, the PCM will need to be replaced or reprogrammed.

  • The reductant injection air controller may be faulty if there is no voltage present on the sensor connector. If the reductant injection air controller is faulty it will need to be reprogrammed.

  • If the P2037 diagnostic trouble code has been set due to low exhaust system back pressure, caused by a high performance aftermarket exhaust system an in line resistor can be installed to fix this problem. Refer to local, state, and federal regulations regarding the removal of emission related components.

Common mistakes when diagnosing the P2037 code

  • The most common mistake when diagnosing the P2037 trouble code is mistaking the oxygen sensor for the reductant injection pressure sensor. These two sensors look similar, and replacing the incorrect one will not solve the problem.

  • It is also common to neglect to inspect the wiring, connectors and terminals for damage.

How serious is the P2037 code?

Aside from the Check Engine Light being on in the dashboard, the only other noticeable symptom will be black smoke bellowing from the tailpipe during acceleration. It is also unlikely for there to be any driveability issues. For this reason the P2037 diagnostic trouble code is not considered a serious one. It should be addressed soon, as driving while this diagnostic trouble code is present for an extended period of time will increase the risk of causing damage to other engine components.

What repairs can fix the P2037 code?

  • Replace or repair loose, broken or corroded wiring
  • Replace or repair loose, broken or corroded terminals
  • Replace or repair loose, broken or corroded connectors
  • Replace faulty reductant injection air pressure sensor
  • Repair internal short in the reduction injection pressure sensor circuit
  • Repair short to ground in the reductant injection pressure sensor circuit
  • Repair short to ground in the exhaust gas temperature sensor (EGTS)
  • Replace high performance aftermarket exhaust system, if it is causing back pressure
  • Repair exhaust leaks that are located upstream from the reductant injection air pressure sensor sensor

Additional comments for consideration regarding the P2037 code

It is typical for the P2037 diagnostic trouble code to be caused by a faulty sensor, damaged wiring, or a connector circuit that has an internal short or a short to ground. Be careful not to mistake the oxygen sensor for the reductant injector sensor, and vice versa.

It is also important to note the possibility that the P2037 diagnostic trouble code has been caused by a high performance aftermarket exhaust. The reductant injection system is an exhaust system that is most often used in diesel engines.

Need help with a P2037 code?

YourMechanic offers certified 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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