yesterday night i started my car and my check engine light was on. i just had a whole new muffler system put on high flow cat and 2.25 inch pipes. so i brought the car to auto zone and my friend ran the code and he said the code is PO 420. its my 02 sencer. should i change the sencer to see if that takes it off or is the cat doing it because its a high flow. my gas miles are really bad in my car i can never get it past 250 miles to a tank its been just pushing 200 now if not 180 to the tank.
the paper the info was on said PO 420 catalyst below threshold bank 1
and the price for a new o2 sencer was after cat $70.00 and before the cat $65.00
If you just changed the cat to a high-flow one... that's it, no doubt. You've installed a cat that is too high-flowing for the computer to compensate for, so it thinks the cat is shot.
What kind of cat you using?
The code is for an O2 sensor in the exhaust manifold (before cat) it should run you about 20.00 id replace that one. That one would effect gas mileage ect. The one after the cat i dont think effects much except montiors the cat to make sure it works. If you replace the first o2 sensor reset ur comp. it should be fine.
In the future if you get th code and it happends to be th 2nd sensor because of the cat then you should get some kind of sim. ect
Bzzzt! Sorry Brandon, that code is the post-converter O2 sensor, not the pre-converter one. The code you're thinking of is P0134.
However, that said... changing the front sensor MAY create enough of a difference (in the readings between the two sensors) that it may make the code go away.... it's an off chance though... no guarantees on that one.
i have the dtc program on my computer i dont know wut the hell i checked..lol anyway i just bought my 1st o2 sensor for 20.00 at autozone and my 2nd one from ebay for 30.0 shipped just got it in today
anyway with the cat you might want to look at the spark plug fouler sim thing. I dont know whats the latest thing to do these days lol
so change both the o2 sencers the one on my header and the one on my cat and that will turn it off? then if it comes on again do they made a performance o2 sencer or something so it can read more air.
i found out whats wrong with my light. i brought the car to the dealer for them to check it out and they found 2 things. the first was the cat is on the wrong back the o2 sencer is closer to the motor and it should be at the other end of the cat. and the sec thing they found was my vavle cover seal is leaking and want $200 to fix it
