Why has my exhaust catalytic converter been stolen?

Thursday February 6 2020

Catalyst converter

Catalyst converter 

By Paul Kaganzi

Hello Paul, a few months ago I bought a 2008 Toyota Corolla which turned up with a check engine fault light on the dashboard. Upon inspection, a mechanic advised that it had a NOX sensor fault and the exhaust catalytic converters had been cut out and stolen. A new exhaust pipe with catalytic converters costs more than Shs9m. The mechanic advised that we could replace the damaged exhaust pipe with an ordinary one and eliminate the fault light. Is the catalytic converter important to this car or can I do away with it? Why was it stolen? Justus

Hello Justus, your Toyota Corolla engine management system like most post 1995 vehicles is configured to work with an emission system designed with a catalytic converter (CAT). Catalytic converters use inbuilt precious metals to chemically break down harmful gases and emission particles.

These precious metals are what the CAT thieves are after. An attempt to eliminate the catalytic converter will affect the car’s emission cleaning system and efficiency, hence the engine fault light and NOX sensor fault.

To appreciate the importance of catalytic converters, you need to understand what they are and how they work. Catalytic converters are ceramic honey comb like emission control devices fitted in the car exhaust pipe between the engine and tail pipe.

They are designed with precious metals such as platinum, palladium, rhodium or nickel which trap and chemically break down (oxidise) toxic gases such as carbon monoxide (CO2) and Nitrogen Oxide (NOX), reducing them to less harmful levels.

Over the last couple of years, demand for new catalytic converters by car manufacturers and parts dealers has risen and this has driven up the price of the precious metals used to build them.


There are scrap dealers who are collecting used catalytic converters for sale to recycling plants who extract and refine the metals for reuse. A gramme of platinum collected after refining costs about $29 (about Shs95,000). Each used catalytic converter can produce between three to seven grammes of platinum which will fetch between $150 to 200 (about Shs549,000 – Shs732,000).

The pressure to find used catalytic converters has driven the vice of CAT theft. All it takes is two burglars in a getaway car to brazenly jack up your car and use welding or cutting tools to pry away the converter and you are lucky if they bother to reseal the exhaust pipe before driving away in a few minutes. Target areas are poorly regulated car storage or parking facilities, washing bays and car repair garages.

This is a global problem so it is possible to import a car with a missing CAT device. It is easy to detect this problem with a computer diagnostic check and inspection. A replacement complete exhaust pipe with catalytic converters is recommended. A new one from a Toyota dealer can cost between Shs7 to Shs9m while a used one may cost about Shs2m to import.