A catalyst (CAT) or catalytic converter is currently used in both diesel and petrol engines. If the manufacturer of the engine isn’t able to drop the amount of emissions below a given threshold without a catalyst. The catalyst will be placed in the exhaust circuit to keep the tailpipe emissions below the threshold. The functionality of our CAT OFF service is mainly aimed for petrol engines with a catalyst or catalytic converter.
The catalyst is there to reduce the amount of harmful emissions. The catalytic converter on petrol engines works best when the mixture of air and fuel is near lambda 1. Diesel engines work with an oxygen ratio of much more than petrol engines. Therefore the catalytic converter for diesel engines is different. It is still able to drop emission on a diesel engine once equipped.
To make sure the catalytic converter is working with mixtures near lambda 1 on petrol engines, lambdasondes need to be installed before the catalyst to tell the engine control unit to inject more (if mixture is lean λ>1) or less (if the mixture is rich λ<1). This method is currently only used on gasoline engines. With the start of OBD regulation (on board diagnostics) on petrol engines the manufacturers were forced to build in a monitoring device that could tell the engine control unit if the catalytic converter still functioned properly. The only sensor or device we are aware of is an additional lambdasonde placed behind the catalytic converter. So once your catalyst working range is dropped near ~50% (depended on manufacturer) the engine control unit will diagnose it with the help of the rear O2 sensor (behind the catalytic) and store a fault code related to the functioning of the catalytic converter. Besides the fault code the “check engine” light will be on since the fault codes is emission related. Karreman Engineering is able to turn off or modify diagnostic monitoring algorithms that monitor the working of the catalytic converter to prevent error codes from malfunction catalytic converters. Once the catalytic converter is not functioning or if it is removed from your vehicle it is possible that it doesn’t meet your country emission regulation. Therefore it is forbidden to use a vehicle with CAT OFF functionality on the public roads there were this is not approved. Karreman Engineering is not responsible for those who use this were not applicable. The user agrees the terms and conditions once the service is payed and the work is executed by our staff.