P2042Reductant Temperature Sensor A Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- 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.
- What you may notice
- MIL and DEF system warning
- DEF heating or dosing may be restricted
- Likely causes
- LikelyOpen circuit or loose connector at the pump/supply module
- PossibleFalse setting at low battery voltage in frost (Volvo/Mack)
- PossiblePoor sensor ground
- RareTemperature sensor in the pump unit defective
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €50 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.