Faulty reductant injection air pressure sensor; Damaged or corroded wiring or connector at the sensor; Leaking or restricted air pressure line to the sensor; Clogged or failed air pressure pump or compressor; Exhaust system blockage or restriction affecting air pressure; Powertrain control module software issue or internal fault

DTC codes / P20xx · Fuel and air metering and auxiliary emission controls / P2037

P2037Reductant Injection Air Pressure Sensor Circuit

Q: What does code P2037 mean?

Reductant Injection Air Pressure Sensor Circuit. P2037 indicates that the powertrain control module has detected an abnormal signal from the reductant injection air pressure sensor, which monitors the air pressure used to help inject diesel exhaust fluid into the exhaust stream. The computer compares the sensor's voltage or pressure reading against expected values and sets this code when the signal falls outside the valid range or fails a rationality check.

P2037 indicates that the powertrain control module has detected an abnormal signal from the reductant injection air pressure sensor, which monitors the air pressure used to help inject diesel exhaust fluid into the exhaust stream. The computer compares the sensor's voltage or pressure reading against expected values and sets this code when the signal falls outside the valid range or fails a rationality check.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering and auxiliary emission controls

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Reduced engine power or limp mode triggered by the powertrain control module
A message on the dash indicating low reductant or a fault in the emissions system
Rough running or hesitation if the air pressure fault affects DEF injection quantity
Increased diesel exhaust fluid consumption in some cases
Failed emissions test due to an incomplete or failed monitor

Common causes, most likely first

Faulty reductant injection air pressure sensor
Damaged or corroded wiring or connector at the sensor
Leaking or restricted air pressure line to the sensor
Clogged or failed air pressure pump or compressor
Exhaust system blockage or restriction affecting air pressure
Powertrain control module software issue or internal fault

How to diagnose and fix it

Use a scan tool to verify the code and check live data for the air pressure sensor signal
Inspect the sensor wiring and connector for damage, corrosion, or loose pins
Check the air pressure lines for leaks, cracks, or blockages
Test the air pressure pump or compressor for proper operation and output
Compare sensor readings with a known good gauge or manual pressure test
Replace the air pressure sensor if it fails testing or shows erratic readings
Clear the code and perform a road test to confirm the repair and monitor readiness

Don't overlook the air pressure pump

A weak or failing air pressure pump often causes this code without setting a pump-specific fault, so testing pump output is critical.
The sensor may be misdiagnosed when a clogged DEF injector or restricted line causes pressure readings to fall out of range.
Corroded connectors at the sensor are a common cause on vehicles exposed to road salt and moisture.
After repairs, the reductant injection monitor may require a specific drive cycle to complete and turn off the light.
This code does not always mean the sensor itself is bad; the PCM may set it due to a rationality error caused by another component in the air pressure system.

Can I keep driving with P2037?

It is generally safe to drive with P2037, but avoid heavy loads and long trips until diagnosed, as continued driving may lead to reduced power or increased emissions. If the engine enters limp mode, seek service promptly.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.