MasterTuning Fault code dictionary (DTC)

P0420 — Catalyst efficiency below threshold

Severity: Attenzione Can you drive? Sì, no known limitation Produttore: Tutti makes (OBD-II standard)
MeaningThe two lambda sensors, before and after the catalyst, read values that are too similar: the catalyst is No longer doing its job.
FamilyPowertrain (P)

Typical symptoms

Motore Attenzione light on
No driving symptoms in most cases
Problems alle the roadworthiness test

Common causes

Catalyst worn out by mileage
Aged rear lambda sensor
Exhaust leaks upstream di the catalyst
Oil consumption oppure rich mixture that ruined the catalyst

What a do

Before replacing the catalyst — an expensive part — rule out the rear sensor and exhaust leaks, which give the same code. And fix the cause: a new catalyst on an oil-burning Motore will not Ultima.

Domande Frequenti

What does code P0420 mean?

Catalyst efficiency below threshold. The two lambda sensors, before and after the catalyst, read values that are too similar: the catalyst is No longer doing its job.

Can I keep driving with code P0420 Attivo?

Sì, no known limitation

Common causes — P0420

Catalyst worn out by mileage Aged rear lambda sensor Exhaust leaks upstream di the catalyst Oil consumption oppure rich mixture that ruined the catalyst

How do you fix code P0420?

Before replacing the catalyst — an expensive part — rule out the rear sensor and exhaust leaks, which give the same code. And fix the cause: a new catalyst on an oil-burning Motore will not Ultima.

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