Reductant Injection Air Pressure Sensor A Circuit
What it means
P2037 is a diesel emissions code: the reductant (DEF/urea) injection air pressure sensor circuit is out of range. This sensor monitors the air-assist pressure used to atomize diesel exhaust fluid in the SCR system. The engine keeps starting and running, but persistent SCR faults can trigger reduced power or a limp mode, so it's worth addressing. The usual cause is the sensor, its wiring, or an air-supply fault.
Can I keep driving? The engine still starts and drives, but the diesel emissions (DEF/SCR) system can trigger reduced power or a limp mode over time — get it addressed before it derates.
Common symptoms
What you'll notice
- Check-engine light on
- DEF/emissions system warning message
- Possible reduced power or limp mode if the fault persists
- Otherwise normal starting and driving
Common causes
Most likely first
- Faulty reductant injection air pressure sensorLikely
- Damaged wiring or connector in the sensor circuitCommon
- Air-assist supply pressure fault in the DEF metering systemCommon
- Faulty DEF/emissions control module or PCMLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and compare the sensor reading to actual air-assist pressure.
- Inspect the sensor wiring and connector for damage, opens, or corrosion.
- Check the air-assist supply lines and pump for leaks or low pressure.
- Test the sensor and replace it if it reads out of range.
- Follow the manufacturer procedure to verify DEF dosing, then clear and re-test.
FAQ
Quick answers
Is it safe to drive with P2037?+
Can I just clear P2037?+
Related codes
Often seen with P2037
Read & clear P2037 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.