P04F5
Catalyst Heater Circuit Low Bank 2
Generic OBD-II
Real-world scan data
Seen in
35
scans in the past year
Found in
<0.1%
of scans
<0.1%
of scans that found faults
Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.
Common symptoms
What you'll notice
- Check the wiring and connections to ensure they are secure and properly connected.
- Inspect the oxygen sensors for any damage or contamination and replace them if necessary.
- Clean or replace the catalytic converter if it is clogged or not functioning properly.
- Check the fuel injectors for any blockage or malfunction and clean or replace them as needed.
Common causes
Most likely first
- Faulty oxygen sensor
- Malfunctioning catalytic converter
- Defective catalytic converter temperature sensor
- Loose or damaged wiring or connectors in the catalyst heater circuit
- Engine control module (ECM) failure
How to diagnose & fix
Work through it in order
- Check engine light illuminates
- Decreased engine performance or power
- Poor fuel efficiency
- Rough idling or engine stalling
- Failed vehicle emissions test
Read & clear P04F5 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.