p0420
Moderate
Infiniti · Sedans
Catalyst System Efficiency Below Threshold (Bank 1)
Quick Answer
Error code P0420 on your Infiniti Sedans 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
Verify oxygen sensor operation
2
Check for exhaust leaks using visual inspection
3
Monitor catalytic converter temperature
4
Inspect catalytic converter for damage
5
Replace catalytic converter if faulty
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 clamps
Gaskets and sealant
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