How to Clean a Catalytic Converter (CAT) without Removing it

Do you have a P0420 error code flashing on your dashboard? Worry not, this post is for you. Your CAT may be clogged but there is no need to remove or replace it at first instance. It can cost you lots of money to replace a CAT without forgetting the labor cost.

Catalytic converter for E30 325i. Installed @ 176844mi Pulled @ 197091mi

Check for internal oil leaks
The CAT can get clogged by oil entering the cylinders and burning inside. You should repair the internal oil leaks before trying to repair the CAT without removing it. The oil leaks may be due to clogged crankcase ventilation or broken piston rings. You can check your oil level because if there are leaks, your engine oil level will be going down.

Add a CAT Cleaner to your fuel tank
If there are no oil leaks, then you can consider a simple DIY trick by using a solution like the OXICAT – Oxygen Sensor & Catalytic Converter Cleaner. This should be around $16 on Amazon. Refill your fuel tank with fuel at full level and pour the whole of the product in the tank. The product is compatible with all kinds of engines – petrol, diesel or hybrid. This will clean the front and rear oxygen sensors, the catalytic converter and the exhaust system at the same time.

Rev the engine at high RPM
Test drive your car. If you are lucky, the product can start to work instantly and you may no more be getting the error code on your dashboard. If that’s not the case, drive your car a few miles to see if your car runs better. Further, drive your car at high RPMs over 4000 for a long distance for around 30 minutes. This will allow the solution to reach the hot CAT and dissolve the clogged parts.

Note: This product is only a cleaner for CAT which may have run with some oil burn previously. The Oxicat solution will not repair mechanical faults if the CAT is already cracked, broken or too clogged.

While running the car at high revs, make sure that there is no oil deposit on your CAT as it could ignite with heat. You should also be paying attention to your coolant temperature at all time to avoid overheating the engine and further compliCATing things!

If the cleaner did not work for your vehicle, you can still remove the CAT and put in a bath of Lacquer thinner. If still not good, it may need to be replaced. You can also read further from this blog post: Can a clogged catalytic converter be unclogged? If still no result, you will need a professional mechanic to save the car.

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