p0420
Moderate
Maserati · Sedans & Sports Cars
Catalyst System Efficiency Below Threshold (Bank 1)
Quick Answer
Error code P0420 on your Maserati Sedans & Sports Cars means: Catalyst System Efficiency Below Threshold (Bank 1). This is usually fixable — see the step-by-step guide below.
Affected Models
Likely Causes
  1. Faulty catalytic converter
  2. Oxygen sensor malfunction
  3. Engine misfire causing excess fuel
  4. Exhaust leak in catalyst area
  5. Bad fuel pressure regulator
How to Fix It
1
Diagnose with OBD-II scanner for related codes
2
Inspect catalytic converter for physical damage
3
Check oxygen sensors before and after catalyst
4
Look for exhaust leaks
5
Monitor fuel pressure and trim values
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
Gasket seal kit
Related Error Codes
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