P0420

Catalyst System Efficiency Below Threshold Bank 1

Medium

What does code P0420 mean?

Powertrain code — it relates to the engine, fuel injection, exhaust or gearbox. System : engine.

Severity — Medium. Fix it soon. The car still runs, but expect higher fuel use and a worsening fault.

Other models with this code

Detailed repair guides available for this code:

Frequently asked questions

Can I drive with code P0420?

Fix it soon. The car still runs, but expect higher fuel use and a worsening fault.

How much does it cost to fix code P0420?

It depends on the affected part and your model. Expect around 80–150€ for the part itself, plus labour if a garage does the work. Check the guide for your model below for a precise estimate.

Can code P0420 clear itself?

A code can clear on its own if the fault was intermittent, but it comes back until the cause is fixed. Clearing the code without repairing solves nothing.

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