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A clogged catalytic converter creates exhaust back-pressure: the engine “cannot breathe”, loses power and runs hotter. If instead it is simply worn out, the typical fault is P0420, efficiency below threshold.

Typical symptoms

• Progressive loss of power, especially at high revs
• Acrid smell of rotten eggs
• Rising consumption and high temperatures under the car
• Engine light with code P0420 or P0430
• Metallic rattle from the exhaust if the monolith has crumbled

Why it gets damaged

• Prolonged rich mixture (injectors, lambda sensor, MAF)
• Repeated misfires melting the monolith
• Oil consumption due to rings or turbo
• Impacts or corrosion of the casing

How it is checked

• Measuring the exhaust back-pressure: the most reliable test
• Comparing the upstream and downstream lambda sensors
• Checking inlet/outlet temperatures

Important: replacing the catalytic converter without fixing the upstream cause means ruining the new one too.

How MasterTuning helps

We check the component with real measurements, not by elimination: flow rates, pressures, corrections and signals read directly from the ECU. We repair, replace and recalibrate the software when needed. Centres throughout Italy.

Read more: what is ECU remapping · vehicle database · find an installer

Want an accurate diagnosis? Contact MasterTuning and book at your nearest centre.

Frequently asked questions

Does code P0420 mean the catalytic converter needs replacing?

Not always: it can be due to the rear lambda sensor, exhaust leaks or a rich mixture. These must be ruled out before replacing the converter.

Can you drive with a clogged catalytic converter?

Best avoided: the high back-pressure strains the engine and can damage valves and the turbo.

How long does a catalytic converter last?

If the engine is in good order it can exceed 200,000 km; a rich mixture and oil consumption shorten its life considerably.