OBD-II code · Powertrain (generic)
P04F6 Catalyst Heater Circuit High Bank 1
Same as P04F4 with the line shorted to supply or open - the ECU measures higher voltage than the commanded duty cycle allows.
Is it safe to drive with P04F6?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelyControl line shorted to supply
- PossibleOpen in heater element or harness
- Less likelyConnector pins corroded - high contact resistance
Symptoms
- Check engine light on
- Failed emissions inspection
- Possibly slightly increased fuel consumption
- Sulfur (rotten egg) smell from exhaust under load
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1.5–5 h
- Emissions test
- Likely to fail
- Parts involved
- Electric Catalyst Heater B1
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.