p0420
Moderate
Dodge · Sedans & Muscle Cars
Catalyst System Efficiency Below Threshold (Bank 1)
Quick Answer
Error code P0420 on your Dodge Sedans & Muscle Cars 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
Scan for related misfire codes
2
Test oxygen sensor readings pre and post catalyst
3
Inspect exhaust system for leaks
4
Replace catalytic converter if necessary
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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