Catalyst Heater Circuit Intermittent Bank 1

Common symptoms

What you'll notice

• Check and replace the oxygen sensor in Bank 1.
• Inspect and repair any damaged wiring or connectors in the catalyst heater circuit.
• Clean or replace the catalytic converter in Bank 1.
• Verify the operation of the engine control module (ECM) and perform any necessary reprogramming or updates.
• If all else fails, consider replacing the ECM itself.

Common causes

Most likely first

1. Faulty oxygen sensor
2. Malfunctioning catalytic converter
3. Wiring issues in the catalyst heater circuit
4. Faulty engine control module (ECM)
5. Exhaust leak in the catalytic converter area

How to diagnose & fix

Work through it in order

1. Check engine light illuminates on the dashboard
2. Reduced engine performance or power
3. Increased fuel consumption
4. Failure to pass emissions test
5. Delayed or rough engine start