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.
Affected components
- Electric catalyst heater b1
Common causes
- High likelihood: Control line shorted to supply
- Medium likelihood: Open in heater element or harness
- Low likelihood: Connector pins corroded - high contact resistance
Possible symptoms
- Check engine light on
- Failed emissions inspection
- Possibly slightly increased fuel consumption
- Sulfur (rotten egg) smell from exhaust under load
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
Related codes
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.