p0420
Moderate
Jeep · SUVs
Catalyst System Efficiency Below Threshold (Bank 1)
Quick Answer
Error code P0420 on your Jeep 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
Verify with two oxygen sensor readings before and after converter
2
Inspect for exhaust leaks near converter
3
Check for engine codes causing misfires
4
Test catalytic converter with back pressure gauge
5
Replace converter if efficiency is below 85%
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 sensors
Exhaust gaskets
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