Powertrain, generic (extended)

P2AB1 Catalyst Heater Control Module Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P2AB1 reports that the control module of an electrically heated catalyst does not work as it should, for example because its self-test fails or the heating it delivers does not match the demand. Such heaters bring a catalyst to working temperature right after start or in low-load driving. According to DieselNet, Vitesco's Emicat heating disc went into two 48-volt mild-hybrid diesel van models from 2022 to warm up the SCR catalyst, after an earlier small-scale use on Audi's 3.0 TDI from model year 2014. No manufacturer documents P2AB1 publicly. CARB requires heated catalysts to reach their design temperature within a period the manufacturer sets after start. A failed switching stage or corrupt software are plausible causes; circuit faults of the heater itself are P0429 and P0439.

Likely causes

Internal fault in the heater control module (power stage or self-test)
Module software fault, update may be available
Module overheated due to poor cooling or high ambient heat at its mounting

Symptoms

  • Check engine light on
  • Higher emissions after cold start; inspection may fail
  • Driving behaviour largely unchanged

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–2,500
Time1–5 h

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

Parts involved

catalyst heater modulecatalyst heater element

Related codes

P2AB2P0429P0439P0423P0433

References: law.cornell.edu, dieselnet.com, patents.google.com.