Fault Family System: Powertrain (P-Codes) 13 SAE Codes

Reductant Injection Air Pressure Sensor

Diagnostic & Technical Explanation

Code P2037 (Reductant Injection Air Pressure Sensor A Circuit) applies to air-assisted DEF dosing systems, where compressed air atomizes the reductant spray, and monitors the pressure sensor(s) that confirm adequate air pressure reaches the injector. The ECM flags a sensor circuit fault, an implausible reading relative to a second sensor (A/B correlation), or a pressure reading that is simply too low or too high for atomization to work, most often from a leaking air line fitting or a clogged inline air filter rather than the sensor itself.

These 13 diagnostic trouble codes share one detection mechanism and one repair path, which is why MechanicDB groups them into a single authored fault family rather than repeating the same explanation 13 times.

Codes in this family (13)

Code	Definition	Repair coverage
P2037	Reductant Injection Air Pressure Sensor A Circuit	3 ranked fixes
P2038	Reductant Injection Air Pressure Sensor A Circuit Range/Performance	3 ranked fixes
P2039	Reductant Injection Air Pressure Sensor A Circuit Low	3 ranked fixes
P2040	Reductant Injection Air Pressure Sensor A Circuit High	3 ranked fixes
P2041	Reductant Injection Air Pressure Sensor A Circuit Intermittent	3 ranked fixes
P209A	Reductant Injection Air Pressure Sensor B Circuit	3 ranked fixes
P209B	Reductant Injection Air Pressure Sensor B Circuit Range/Performance	3 ranked fixes
P209C	Reductant Injection Air Pressure Sensor B Circuit Low	3 ranked fixes
P209D	Reductant Injection Air Pressure Sensor B Circuit High	3 ranked fixes
P209E	Reductant Injection Air Pressure Sensor A/B Correlation	3 ranked fixes
P20CA	Reductant Injection Air Pressure Leakage	3 ranked fixes
P20E6	Reductant Injection Air Pressure Too Low	3 ranked fixes
P20E7	Reductant Injection Air Pressure Too High	3 ranked fixes

What this page does not show

This page publishes the fault mechanism and the code index. The licensed dataset adds, for every one of the 15,886 codes, the full authored repair set (56,729 procedures in total) with the fields deliberately withheld here:

Procedures 2..n after the first-listed procedure
Aftermarket parts cost ranges in USD (est_parts_cost_min/max_usd)
Professional labor-hour estimates (est_labor_hours)
Step-by-step diagnostic and repair instructions
Replacement-part mappings and catalog lookups
6,637 manufacturer-specific OEM codes across 32 makes ($149 tier)

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