2022 Lexus P0420: What It Means & Is It Safe to Drive?
P0420 on the 2022 Lexus: Catalyst System Efficiency Below Threshold (Bank 1). Here's what it means, what usually causes it, what repairs typically cost, and whether it's safe to keep driving.
What this code means
The downstream oxygen sensor detects that the catalytic converter is not storing or converting exhaust properly. This is one of the most common check engine codes.
Common causes on the 2022 Lexus
- Failed or aging catalytic converter
- Faulty downstream oxygen sensor
- Exhaust leak before or after the catalyst
- Engine misfire or rich/lean condition damaging the catalyst
Symptoms
- Check Engine Light on
- Often no drivability issues
- Possible failed emissions test
- Rotten egg smell in some cases
Typical fixes
- Replace catalytic converter
- Replace oxygen sensor(s)
- Repair exhaust leaks
- Fix underlying fuel/ignition issues first
Repair cost range
For a 2022 Lexus, repairs for P0420 typically fall between $400 and $2400, depending on the root cause and labor rates in your area.
Known issues on Lexus
Lexus P0420 on 3.5L V6 (2GR-FE) engines shares Toyota's strong reliability record—cats typically last 150k+ miles. When P0420 does appear, check the downstream O2 sensor connector for corrosion before condemning the converter, especially on vehicles in salt-belt regions. IS250 2.5L 4GR-FSE uses direct injection; carbon buildup on intake valves can alter combustion and fuel trim enough to trigger false P0420 readings. On GX470 4.7L V8, the vehicle has four O2 sensors; confirm which bank's sensor is reading low before ordering parts.
Most commonly affected models