Catalyst Heater Circuit Intermittent Bank 1
Same as P04F4 with intermittent or erratic signal - typically a connector or harness fault on the heater feed.
Affected components
- Electric catalyst heater b1
- Catalyst heater wiring b1
Common causes
- High likelihood: Intermittent contact at connector
- Low likelihood: Connector with intermittent contact under vibration
- Low likelihood: Harness routed against vibrating component
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.