P2AB1
Catalyst Heater Control Module Performance
The ECM detects that the catalyst heater control module does not respond to commands within the expected window. Heating output is reduced or absent during catalyst light-off.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: hard
Symptoms
- Check engine light on
- Failed emissions inspection
- Possibly slightly increased fuel consumption
- Sulfur (rotten egg) smell from exhaust under load
Common causes
Ordered by how often each turns out to be the cause.
- Internal control module faultCommon
- Communication with ECM degradedPossible
- Module software outdated, reflash may resolveLess likely
Parts involved
- Catalyst Heater Module
- Catalyst Heater Element
P2AB1 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.