p0420
Moderate
Lexus · SUVs
Catalyst System Efficiency Below Threshold (Bank 1)
Quick Answer
Error code P0420 on your Lexus SUVs means: Catalyst System Efficiency Below Threshold (Bank 1). This is usually fixable — see the step-by-step guide below.
Affected Models
Likely Causes
How to Fix It
1
Read and clear fault codes with OBD-II scanner
2
Inspect catalytic converter for damage
3
Test oxygen sensors before and after converter
4
Check exhaust system for leaks
5
Run vehicle under load to verify repair
Pro Tip
This fix requires some technical knowledge. If you're unsure about any step, consider contacting support or a qualified technician.
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