Powertrain
generic / SAE
P04F2
Catalyst Heater Supply Voltage Bank 1
The electric catalyst heater on bank 1 - used on hybrids and modern petrol cars to bring the catalyst above light-off temperature within seconds of cold start - reports that its supply voltage is outside the expected window. The heater cannot deliver the rated power, so cold-start emissions rise until the catalyst reaches light-off conventionally.
SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number4 / F2
Possible causes
- Heater supply voltage low or unstable high
- DC/DC converter fault on heater rail medium
- High contact resistance in supply low
Symptoms
- Check engine light on
- Failed emissions inspection
- Possibly slightly increased fuel consumption
- Sulfur (rotten egg) smell from exhaust under load
Inspection / repair
- Difficulty: hard
- DIY: shop recommended
- Estimated cost: 400–2500 €
- Estimated time: 2–6 h
- Component: electric catalyst heater b1
- Component: high voltage supply
- Component: dc dc converter
- MIL / check engine light
- emissions-relevant
Sources
References
sae:J2012