OBD-II code · Powertrain (generic)
P0422 Main Catalyst Efficiency Below Threshold (Bank 1)
Generic main catalyst efficiency code on bank 1 — used by some manufacturers in addition to or instead of P0420. Indicates the same root cause — degraded oxygen storage in the main catalyst.
Is it safe to drive with P0422?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelyCatalyst aged or contaminated
- PossibleOxygen sensor drift
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
- 1.5–5 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Catalytic Converter, Oxygen Sensor Upstream, Oxygen Sensor Downstream
Related codes
- P0420Catalyst System Efficiency Below Threshold (Bank 1)
- P0432Main Catalyst Efficiency Below Threshold (Bank 2)
- P041FSecondary Air Injection System Switching Valve A Circuit Low
- P0421Warm Up Catalyst Efficiency Below Threshold (Bank 1)
- P0423Heated Catalyst Efficiency Below Threshold (Bank 1)
- P0424Heated Catalyst Temperature Below Threshold (Bank 1)
- P0425Catalyst Temperature Sensor (Bank 1, Sensor 1)
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.