Powertrain, generic (extended)

P2AB2 Catalyst Heater Control Module Supply Voltage

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P2AB2 points to the power feed of the catalyst heater control module: the voltage it measures at its own supply input lies outside the window in which it may switch the heater. That window matters because these heaters draw several kilowatts; Vitesco's demonstration vehicle used a 4 kW disc, fed in 48-volt mild hybrids from energy recovered while braking, as DieselNet reports. Mitsubishi Electric's patent US5388404A shows the logic behind such a check: the controller first compares battery voltage with a reference and only then closes the heater current switch, guided by a catalyst temperature signal. No manufacturer documents P2AB2 publicly. A blown fuse, a corroded ground, a weak 48-volt battery or a faulty DC/DC converter are typical finds. P0562 and P0563 cover the general system voltage.

Likely causes

Blown fuse or faulty relay in the heater supply
Corroded or loose ground or high-current terminal
Weak 48-volt battery or faulty DC/DC converter in mild-hybrid systems

Symptoms

  • Check engine light on
  • Catalyst heating not available, higher emissions after cold start
  • Further voltage-related fault codes possible

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€30–1,500
Time0.5–4 h

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

Parts involved

catalyst heater modulewiring harness

Related codes

P2AB1P0429P0439P0562P0563

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