Powertrain, generic (extended)

P2037 Reductant Injection Air Pressure Sensor A Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

Some heavy-duty SCR systems do not spray DEF on their own pressure alone but blow it into the exhaust with compressed air, supplied by a compressor or an existing air system; Bosch's first Denoxtronic generation was built this way. A pressure sensor checks that this air is present before dosing. P2037 is the general circuit fault of that sensor. Deutz uses it on the EMR L1 controller (SPN 4335) for two failure types: a ground fault (-F0) and a sensor supply out of range (-1C), while a reading stuck low or open goes to P2039 and a short to battery to P2040. CARB names air assisted injection as part of the reductant delivery that must be monitored. With the air pressure unknown, dosing is normally stopped, and on trucks a power derate may follow.

Likely causes

5 V supply or ground of the sensor interrupted or shorted
Damaged harness or corroded connector at the dosing module
Air pressure sensor failed internally

Symptoms

  • Engine or emission warning lamp on
  • DEF dosing suspended
  • Engine power derate on trucks and machines

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–500
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

reductant air pressure sensorreductant air pump

Related codes

P2038P2039P2040P2041P209AP2059

References: serdia.deutz.com, energy.gov, law.cornell.edu.