So I've been getting a p0420 code when I get my codes read at autozone and I've already replaced the catalytic converter and both 02 sensors and the code still comes back after a couple of days of driving after i reset my trucks computer. My vehicle is a 1996 tacoma with a 2.7 liter and a 5 speed. I was reading the paper autozone gives you after your codes get read and it said that low fuel pressure can also cause this catalyst deficiency. Just wondering if anyone has heard of this. It almost seems possible because on occasion it takes about 15-20 seconds to fire up my truck, almost like my fuel pressure regulator is going out. The fuel pressure regulator went out on my old v6 4runner and it had the same kind of symptoms only i could smell fuel. Anyway, kind of running out of ideas here any help would be appreciated.

 

Did you use AFTERMARKET cats or OEM TOYOTA cats?

I have experienced and since been told that AFTERMARKET cats will not always fix the P0420 code.

Only OEM TOYOTA cats - yes, $$ very expensive $$ will cure a cat-induced P0420 code. It's a flow issue.

I had the P0420 on my '01 5VZFE Tacoma and replaced both cats with aftermarket and still had the code

I would replace your fuel filter and see how that goes if you think it's a fuel pressure/flow issue. Not too expensive. Can't hurt if you have never changed it.

 

I replaced the cat with an lc engineering catylytic converter there suppose to be very close to oem if not the same, fuel filter might not be a bad idea though I might also get my injectors cleaned to the vehicle does have 190,000 miles.

 

My question to you is what brand 02 sensors did you install? i have read numerous times Denso is the only brand you should use. Toyota's dont do well with other brands.