p0420
Moderate
Volvo · SUVs
Catalyst System Efficiency Below Threshold (Bank 1)
Quick Answer
Error code P0420 on your Volvo 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
Check downstream oxygen sensor
2
Inspect catalytic converter for damage
3
Look for exhaust system leaks
4
Check fuel pressure and injector spray
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
catalytic converter
oxygen sensor
exhaust gasket
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