HomeTrouble CodesP2037

P2037 — Reductant Injection Air Pressure Sensor Circuit

Manufacturer-specificPowertrain (engine & transmission)

This code indicates a malfunction in the electrical circuit responsible for monitoring the air pressure within the diesel exhaust fluid injection system. The engine control module has detected voltage or signal values from the reductant injection air pressure sensor that fall outside the expected range. This can prevent proper fluid dosing and affect emissions compliance.

Symptoms

What causes it — most likely first

1. Failed Air Pressure Sensor

The sensor itself often fails internally due to heat or vibration exposure near the exhaust system.

2. Damaged Wiring Harness

Wires near the SCR system are exposed to high heat and road debris, leading to opens, shorts, or high resistance.

3. Corroded Electrical Connector

Moisture and chemical exposure can cause terminal corrosion at the sensor plug, disrupting the signal circuit.

4. Blocked Air Supply Line

Debris or crystallization can block the air line feeding the injector, causing abnormal pressure readings that trigger circuit codes.

5. Faulty DEF Dosing Controller

The module controlling the pump and injector may malfunction, affecting sensor signal interpretation or power supply.

6. Failed PCM/ECM

Internal controller failure is rare and should only be considered after all external components and wiring are verified.

How it's diagnosed

  1. Scan for all stored codes and freeze frame data to confirm the specific circuit fault.
  2. Visually inspect the sensor wiring harness and connector for heat damage, corrosion, or disconnection.
  3. Measure sensor voltage and ground signals with a multimeter to compare against manufacturer specifications.
  4. Check the air supply line for blockages, kinks, or leaks that would affect pressure delivery.
  5. Test the sensor output while activating the dosing system to verify live data response.
  6. Rule out wiring and sensor issues before considering control module replacement.

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationManufacturer-specific (P1/B1/C1/U1)

Frequently asked

Will this code prevent my vehicle from starting?

Usually no, but the vehicle may enter a reduced power mode after a certain number of ignition cycles to comply with emissions regulations.

Is it common to need a new computer for this code?

No, replacing the PCM is rarely the solution; most cases are resolved by repairing wiring or replacing the pressure sensor.

Can I drive with this code active?

Short-term driving is possible, but prolonged operation may lead to reduced performance and eventual no-start conditions due to emissions system lockdown.

Does this affect fuel economy?

Yes, improper DEF dosing can cause the engine management system to alter fuel maps, potentially reducing efficiency.