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U034D Software Incompatibility With Vehicle Thermal Management Control Module

Check engine lightUsually off
EmissionsRelevant
Drive cycleNot required
Limp modePossible

The vehicle thermal management control module commands pumps, valves and fans that keep battery, drive electronics and cabin at their target temperatures. U034D means a partner controller rejects its software or calibration. No manufacturer documents U034D publicly. Audi shows that the software of this unit counts for OBD: on the 2020 Q5 hybrid, thermal management control module 00C5 judged normal temperature differences as faults, stored P0C4300 and P0CE100 and lit the MIL until campaign 80C9 updated it. Porsche reprograms the thermal management unit TME of the Taycan from 2020 together with the high-voltage heater to make cabin heating more robust (WPS9). CARB wants the electronic components that cool or heat hybrid battery and inverter monitored. U02AB is lost contact, U05AC invalid data. Heating, charging or power may be limited.

Likely causes

Thermal management controller on an outdated software level
Thermal management module replaced without programming
High-voltage heater or another partner updated without matching the thermal controller

Symptoms

  • Weak cabin heating or cooling
  • Charging or drive power limited to protect the battery
  • Warning lamp with thermal or coolant codes stored

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€80–1,200
Time0.5–3 h

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

Parts involved

thermal management module

Related codes

U02ABU05ACU032A

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