p0420
Moderate
Genesis · SUVs
Catalyst System Efficiency Below Threshold (Bank 1)
Quick Answer
Error code P0420 on your Genesis SUVs means: Catalyst System Efficiency Below Threshold (Bank 1). This is usually fixable — see the step-by-step guide below.
Affected Models
Applies to all models
Likely Causes
How to Fix It
1
Connect OBD-II scanner and verify fault
2
Perform oxygen sensor voltage test before and after cat converter
3
Inspect exhaust system for leaks
4
Check fuel trim values
5
Verify catalytic converter temperature
Pro Tip
This fix requires some technical knowledge. If you're unsure about any step, consider contacting support or a qualified technician.
Parts You May Need
Catalytic converter
Oxygen sensor
Exhaust gasket kit
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