Nissan P0420 — Meaning, Causes & Fixes

Guidance for the P0420 code on popular Nissan vehicles like the Altima, Sentra, and Rogue.

Common Causes for a P0420 on a Nissan

On many Nissan models, a P0420 code is very frequently caused by a degraded catalytic converter, often one that is integrated with the exhaust manifold.

Pre-Catalyst Failure: Many Nissans have pre-catalysts that can degrade and send debris into the main converter, causing it to fail.
Faulty Air-Fuel Ratio (A/F) Sensor: This is the upstream sensor on a Nissan. A bad A/F sensor is a common cause.
PCV System Issues: A clogged PCV valve can lead to increased oil consumption, which contaminates the catalytic converter.