p0420
Moderate
Acura · SUVs
Catalyst System Efficiency Below Threshold (Bank 1)
Quick Answer
Error code P0420 on your Acura 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
Check exhaust system for leaks using a smoke test
2
Test oxygen sensors before and after catalytic converter
3
Monitor fuel trim values
4
Inspect catalytic converter for damage
5
Replace catalytic converter if damaged
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
Oxygen sensor
Catalytic converter
Exhaust gasket
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