Powertrain
generic / SAE
P0423
Heated Catalyst Efficiency Below Threshold (Bank 1)
Heated (electrically warmed) catalyst on bank 1 fails efficiency monitoring. In addition to standard catalyst aging, faults in the catalyst heater control or supply can cause this code.
SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number4 / 23
Possible causes
- Catalyst aged or contaminated high
- Catalyst heater circuit fault medium
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: 600–2500 €
- Estimated time: 1.5–5 h
- Component: heated catalyst
- Component: catalyst heater
- Component: oxygen sensor downstream
- MIL / check engine light
- emissions-relevant
- drive cycle required
Sources
References
sae:J2012