OBD-II code · Powertrain (generic)
P0439 Catalyst Heater Control Circuit/Open (Bank 2)
The drive circuit for the heated catalyst on bank 2 is open. Heated catalysts use an electrical heating element to reach light-off temperature within seconds of cold start.
Is it safe to drive with P0439?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelyHeater element or wiring open
- Less likelyPin pushed back out of connector body
- Less likelyCracked solder joint inside the module or sensor
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 h
- Emissions test
- Likely to fail
- Parts involved
- Catalyst Heater
Related codes
- P0429Catalyst Heater Control Circuit/Open (Bank 1)
- P0436Catalyst Temperature Sensor Circuit Range/Performance (Bank 2 Sensor 1)
- P0437Catalyst Temperature Sensor Circuit Low (Bank 2 Sensor 1)
- P0438Catalyst Temperature Sensor Circuit High (Bank 2 Sensor 1)
- P043ACatalyst Temperature Sensor Circuit (Bank 2 Sensor 2)
- P043BCatalyst Temperature Sensor Circuit Range/Performance (Bank 2 Sensor 2)
- P043CCatalyst Temperature Sensor Circuit Low (Bank 2 Sensor 2)
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.