Powertrain, generic (extended)

P205C Reductant Tank Temperature Sensor A Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P205C reports the DEF tank temperature signal at the bottom of its range. For voltage-read NTC sensors that means implausibly hot: Ford's 2023 diesels set it below 0.165 V, VW's Touareg below 0.30 V, GM's 2025 DEF controller below 0.3 V (about 75 °C) and GM's 2018 diesel table below 200 Ω, each as short to ground. Careful with older GM trucks: on the 6.6L LML and the 2014 Cruze the value arrives as a CAN raw value, and Low means a raw value under 1, i.e. −55 °C and over 1200 kΩ, the cold side (Type A, 3 s). Ford bulletin 18-2190 replaces the reductant heater and sender assembly on 2011–2015 6.7L Super Duty when P205C appears with P2043, and Hino has P205B to P205D checked before blaming the coolant valve. The high end is P205D.

Likely causes

Signal wire shorted to ground
Faulty sensor in the heater/sender assembly
DEF in the connector bridging the terminals

Symptoms

  • MIL and DEF warning
  • Tank temperature in live data stuck at an extreme
  • Tank heater not working in frost

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–1,200
Time0.5–2.5 h

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

Parts involved

reductant tank temperature sensor

Related codes

P205AP205DP205BP2043P2ADB

References: gsi.ext.gm.com, fordservicecontent.com, static.nhtsa.gov, gsi.ext.gm.com.