Powertrain, generic (extended)

P2044 Reductant Temperature Sensor A Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2044 is set when the signal of reductant temperature sensor A sits below its valid voltage window. As with other NTC thermistors, a low voltage corresponds to a hot reading, so a signal wire touching ground makes the fluid look extremely hot. Deutz lists P2044-00 as a grounded signal of the SCR-side DEF temperature input (SPN 4337) on the EMR L1 main and secondary ECU, kept apart from the tank sensor, whose low fault is P205C. No public table gives voltage or time limits for P2044; CARB only requires out of range and circuit checks for every input that feeds an emission control (13 CCR 1968.2 (f)(15.2.1)). A false hot value can switch off DEF heating in the cold, so frozen lines may follow. Measure the sensor and look for chafing before replacing parts.

Likely causes

Signal wire chafed through to ground
Sensor shorted internally (resistance near zero)
DEF residue in the connector bridging signal and ground

Symptoms

  • MIL and DEF warning
  • Scan tool shows an implausibly high DEF temperature
  • Lines may freeze because heating stays off

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–800
Time0.5–2.5 h

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

Parts involved

reductant temperature sensor

Related codes

P2042P2045P2043P205CP2ACE

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