hey there, i have this 130K acura tl 2005, the check engine suddenly turned on i checked the code and it was this P0420 code
I took it with a mechanich guy he did a tune up, change the spark plugs, engine oil, air filter and all oil filter, and he cleaned i dont what he cleaned but he explained me that it could be the cause
i cleared the code, i drove the car for 1 week and the code turned on again
im just wondering, could it be the catalytic converter or the oxygen sensor, and wich of the 4 oxigen sensors could be?, is there a way to know?
how long can i have the car with this issue? cuz im kinda broke right now
please help !!

 

its the catalytic converter
mine went out a 177k on my 2004 tl
i had to fix right away cause ny has state inspection test on cars each yr and it was going to fail
and it was almost 700 to fix at a local mechanic

 

It's the rear bank pre-cat, near the firewall. You can take it to an exhaust shop and have them install a spacer/"defouler" in the O2 sensor and the light won't return - it's the cheapest method other than replacing the cat.

 

And the daughter's Maxima actually passed inspection with the defouler installed.

 

So it cant be the O2 sensors by any chance?
I actually live in mexico, mechanics are not that expensive as in the us, they would charge 40 or 50 bucks to replace the cat, but cats are expensive... I was hoping to be one or two oxygen sensors...

 

Probably converter, but you can always check the voltage at the rear sensor with a scan tool and see if <.5 volts, if over, I'd say converter.

 

I did this trick about 1200 miles ago, no light so far

 

Well just for the records the check engine light turned off by itself yesterday it it havent come back yet...

 

I was able to clear the code. First i used cataclean and the code came back on. Next I tried Techron, Lucas oil and cleaned the air filter. It came back on. Finally; I did a synthetic oil change; put more Techron and Lucas oil and the code has stayed off and I was able to get the smog inspection done. I also drove the car on the highway for 100 miles. My converter was clogged.


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