Catalytic Issue

About 2.5 years ago I kept throwing a check engine light on my Tacoma. I had it scanned and reset multiple times. It's a P0240 code (Inefficient Cat, Bank 1). I did the quick and easy first. I ran Cataclean first, no change, then I replaced the pre-cat O2. Again it would come on. I dropped the old cat and sure enough it needed to be replaced as the light shinning thru the honeycomb inside was reduced down to about the diameter of a quarter (after 140K miles).

I checked around the dealerships and the part ranged from 900 to 1000 dollars. Too rich for me, so, I decided to get an aftermarket bolt on cat from FlowMaster for about $200.

Installation went fine, reset the check engine light, and all was well for about a week. Then the check engine light came back. I got tired of resetting every other few days. So, I left it on. Now, keep in mind that this issue has not affected mileage or performance.

Dealership's answer is "It's the FlowMaster," you need to buy our catalytic converter. FlowMaster's answer is "It's not our part," you need to check a whole host of things that ran like 4 pages long. Everyone is pointing at one another, and no solution is being resolved.

Are the 1st gen Tacoma's that finicky with their aftermarket converters (this is also sort of pre ODBII)?

Now I know that engineering could have designed it with tight enough specifications that only an OEM part will work. I have heard that other mechanics have had no issues with a bolt on aftermarket on the newer Tacoma's. Any validity to this? Any information would be great as usual.

 

I have a (well-made) Flowmaster too. It wasn't the cat. For me it was both round seals, but don't make the bolts too tight - it could deform the seals.

 

I've never had luck with aftermarket converters.

The only true way you can make sure is to monitor the upstream and downstream sensors after a switch in fuel trim levels when warm, this requires above average diagnostic skills though.

A stupid redneck way to check to see if the cat is working is to simply smell the exhaust once warm, if it stinks of fuel then its likely the cat isn't performing.

Another way to check cat performance is a heat gun from front to back to see if any chemical reaction is occurring.

P0420 is a pretty reliable code if it's the only one setting. It takes quite a few trips to trigger and is dependant on both o2 sensors operating.

I would say get it diag'd properly with the scan tool and graph chart but at this point where would that get you, no refund is likely.

You can solve it with a downstream o2 sensor simulator. http://www.lceperformance.com/Rear-O2-Simulator-2TR-FE-2-7L-Tacoma-p/1020307.htm But even that has it's possiblity of not working.

 

I had the same code on my 2000 Tacoma with 128000 miles, reset and light came back after 100 miles. After reading several post I did the following. Replaced spark plugs (from dealer), replaced air filter, cleaned MAF sensor and both O2 sensors with MAF cleaner from auto zone. Have over 2k miles and light is still off.