Powertrain, generic (extended)

P2045 Reductant Temperature Sensor A Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2045 covers the opposite end: the voltage of reductant temperature sensor A is higher than any real temperature would produce. With an NTC element this reads as very cold, which is what an interrupted ground, a disconnected plug or a signal wire touching battery voltage cause. Deutz files P2045-00 as a short to battery for the DEF sensor outside the tank (SPN 4337); an open circuit gets its own entry, P2042-13. The tank temperature sensor counts separately, with its high fault under P205D. As no maker publishes thresholds for P2045, the CARB rule on input circuit monitoring (section (f)(15.2.1) of 13 CCR 1968.2) is the frame. A false cold value may keep the heater running and delay dosing after start. Check the plug, the ground and the sensor resistance at a known temperature.

Likely causes

Open sensor ground or unplugged connector
Signal wire shorted to battery or supply voltage
Sensor element open internally

Symptoms

  • MIL and DEF warning
  • Scan tool shows DEF temperature near the lower limit
  • Dosing may start late after a cold start

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

P2042P2044P2043P205DP2ACF

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