Powertrain, generic (extended)

P2042 Reductant Temperature Sensor A Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2042 concerns reductant temperature sensor A, which is a different part from the tank temperature sensor of P205A ff. The makers that document it place it outside the tank: Deutz assigns P2042 to the DEF temperature sensor of the SCR system (J1939 SPN 4337), while its tank sensor (SPN 3031) uses P205A; failure type 13 marks an open circuit, F0 a ground fault. Volvo and Mack describe P2042-01 (US17/OBD16 engines) as a test of the temperature sensor in the DEF pump and warn in KC-2015 that low battery voltage with ambient and tank below 0 °C logs it with nothing wrong; then the pump must not be replaced. Hino also separates tank and pump sensors. Short to ground and to battery are P2044 and P2045. Drivers see the MIL and a DEF warning.

Likely causes

Open circuit or loose connector at the pump/supply module
False setting at low battery voltage in frost (Volvo/Mack)
Poor sensor ground
Temperature sensor in the pump unit defective

Symptoms

  • MIL and DEF system warning
  • DEF heating or dosing may be restricted

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–900
Time0.5–3 h

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

Parts involved

reductant temperature sensorreductant pump

Related codes

P2043P2044P2045P2046P205AP2ACC

References: serdia.deutz.com, serdia.deutz.com, static.nhtsa.gov.