Powertrain
generic / SAE
P04F9
Catalyst Heater Circuit Intermittent Bank 2
Same as P04F8 on bank 2. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number4 / F9
Possible causes
- Intermittent contact at connector high
- Connector with intermittent contact under vibration low
- Harness routed against vibrating component 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: 200–1500 €
- Estimated time: 1–4 h
- Component: electric catalyst heater b2
- Component: catalyst heater wiring b2
- MIL / check engine light
- emissions-relevant
Sources
References
sae:J2012