So ive been reading through the post about the P0420 code. Turns out thats exactly what my computer is reading, so how bad is it?...i mean how long can i go avoidin the problem?...and as far as the low pressure light...my fac. radio doesnt even have the tir pres. reset function...n ive tried a million times to do it wit the runnin lights...so i hope someone can provide some answer for me thankz...Laterz



02' on 22's

 

Have anything aftermarket on your car? How many miles?

 

just rims thats it...n its got 106,000 miles

 

then it's either time for a new cat, or a new o2 sensor, but either way, if you don't have an aftermarket system, p0420 is not a normal code to throw...

 

The P0420 is the cat. What year is your Monte? If it's an '01 or '02 check out this post https://montecarloforum.com/m_12459/tm.htmMine was one of those and GM fixed it at no cost.

 

well...i took the monte carlo to the dealership today and they said a aftermarket converter had already been installed...so wat r the chances of it being the O2 Sensor for sure?

 

Probably that aftermarket cat causing it. There's a way to test the O2 sensor but you'll have to do a search on the net. I found at one time when Advance said my O2 was causing the P0420 code and was researching it. Most everything I found said that if it's the sensor then it will throw a code for the sensor and not for the cat.

 

well my instructor said it might be the O2 sensor to...i just dont want to waste the money...but i will do some research

 

Well it isn't a waste of money. There are only a few things that cause this code. A cat and an O2 sensor...it's just a matter of which sensor is throwing the code, that will be the challenge. Good Luck.

 

Well, if it helps any, I've heard that it's a good idea to replace them at 100k miles anyway. hmm, I guess I really should replace mine too.