The short answer is that our strongest gasoline fuel additive, B-12 Chemtool Total Fuel System Clean-Up (part #2616), and a good tune-up might indirectly solve your problems. The long answer is as follows…. There are no true oxygen sensor cleaners that are safe to put through your engine. While some people choose to remove them and use a wire brush or an aerosol cleaner to remove deposits, we do not recommend trying to clean O2 sensors. We feel their function is too critical to risk damaging the sensors and possibly (and erroneously) altering the air-fuel mixture. Additionally, the threads of the sensor(s) may not survive multiple removal and installation cycles. Sometimes they don’t even survive one complete cycle! As for the catalytic converter, you cannot directly clean one while it is still on the car, because anything that is safe to run through the engine will be converted to CO2, O2, and N2, none of which will do any cleaning. From that standpoint, a “catalytic converter cleaner” is gimmicky. Again, though, you do have some options. Because catalytic converters are “self cleaning” under certain conditions, they should actually last the life of the car. If the “guts” are physically intact and there’s just some build up on the catalysts, then running a high-performance fuel system cleaner like 2616 and making sure the engine is properly tuned-up can help tremendously. The combination of the two actions idealizes or “fixes” the combustion products and allows the catalytic converter to start burning/shaking off the deposits and becoming active again. However, if the catalysts or the supporting structures are physically damaged, then nothing can be done to resurrect them. This can happen, for instance, as a result of prolonged unburned fuel exiting the combustion chamber due old or bad spark plugs, broken spark plug wire, dirty combustion chambers, etc. When this occurs, the catalytic converter can get too hot and start physically breaking apart over time. If this has happened, then no cleaner in the world can fix it, and the component will simply have to be replaced. It’s for these reasons that our recommendation is two-fold. Using 2616 will clean fuel lines, fuel injectors, intake valves (in non-direct-injection motors), and combustion chambers. Then getting the vehicle tuned-up—paying particular attention to the ignition system, including the spark plugs and plug wires—will ensure you’re not allowing unburned fuel into the exhaust system. After running the 2616 and getting the tune-up, you’ll need to do some extended driving of the vehicle, preferably on the highway or anywhere else you don’t have a lot of start-stop cycles, in hopes of burning off any deposits that have fouled the catalysts. Best of luck!