Powertrain, generic · Hybrid propulsion

P0C43 Hybrid/EV Battery Pack Coolant Temperature Sensor A Circuit Range/Performance

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modeNo

P0C43 flags battery coolant temperature sensor A as electrically valid but not believable. GM's 2019 hybrid tables describe a cold-soak comparison: once all high-voltage contactors and the battery heater have been off for at least 14,400 s, the hybrid controller compares inlet coolant temperature with the average cell temperature and with outside air, failing when the gaps reach about 23 °C and 22 °C; 8 s out of 10 s set a Type B code, so the MIL follows on the second trip. Audi uses P0C4300 in the thermal management module of the 2020 Q5 TFSI e. Bulletin 2059530 and update 80C9 explain that the stored limits were set too tightly for everyday conditions, so the code and P0CE100 appeared without a defect; new software fixes it. CARB demands rationality checks for battery thermal inputs.

Likely causes

Too tight plausibility limits in the control software (Audi Q5 TFSI e, update 80C9)

Coolant sensor A drifting away from its characteristic

Added resistance in the sensor circuit shifting the reading

Symptoms

MIL after a cold start, often with no other complaint
Battery thermal management working on substitute values

Repair estimate

DifficultyHardWorkshop job

Parts and labour€0–400

Time0.5–2.5 h

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

Parts involved

hv battery pack coolant temp sensor awiring harnessbms

References: gsi.ext.gm.com, static.nhtsa.gov, static.nhtsa.gov, law.cornell.edu.