Powertrain, generic

P0E81 Auxiliary Cooling System Coolant Temperature Sensor A Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P0E81 is the general circuit code for temperature sensor A in an auxiliary cooling loop, a coolant circuit separate from the main engine loop, such as a heater loop of a plug-in hybrid or a loop that cools electric drive parts. The module sees a signal it cannot use at all, without classing it as too low, too high or implausible. No manufacturer documents P0E81 publicly. Ford's 2019 hybrid summary describes a comparable sensor, ECT2, placed between the electric PTC heater and the heater matrix, and checks its circuit through the analog input under P2184 and P2185. Volvo uses the term auxiliary cooling system for its T8 hybrids under P0EA7. CARB requires temperature sensors of this kind to be checked for circuit continuity. The more specific siblings are P0E82 to P0E84.

Likely causes

Loose, corroded or unplugged sensor connector
Failed temperature sensor A
Damaged signal or reference wire

Symptoms

  • Check engine light
  • Heater or auxiliary pump runs on default values

Repair estimate

DifficultyEasyDIY possible
Parts and labour€40–250
Time0.3–1.5 h

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

Parts involved

aux cooling coolant temp sensor awiring harness

Related codes

P0E82P0E83P0E84P2183P0EA7

References: fordservicecontent.com, static.nhtsa.gov, law.cornell.edu.