CEL Problem: PO421?

[Frozen]

Alright, so my CEL came on and I went to a repair shop to get it fixed. The trouble code came up as PO421 and so they replaced one of my o2 sensors, I don't know if it was my post-cat or pre-cat one but I know they only replaced one. The cost was $227 + tax. Was I ripped off? How much should I be paying?

Also, a day later the CEL came on again. I'm not sure if the other O2 sensor needs to be replaced or if I have a fuel leak, a bad cat, I don't know.

I've also noticed that when I drive after sitting at a light a puff of white smoke will come out of my exhaust or when I shift gears a puff of white smoke will come out. That's normal, right?

NOTE: I know nothing about cars and repairing them.

 

[Metallic36]

Here is some info: http://www.mazdas247.com/forum/showthread.php?t=123725211&highlight=p0421

 

[jonridinhi]

Definatlly try the non fouler trick. i tried the capaciter and resistor rig and it was hard to do and worked for about 1,000 miles and light again. I did the non fouler and have not had an issue for over 10,000 miles since i installed it. just rest your ecu after fixing it to get it to reset.

 

[Frozen]

What does the non fouler trick do? Would I be able to get a mechanic to do that? I have no experience with cars and repairing them, btw. Only thing I know how to do is an oil change and change the bulbs on my headlights, haha.

Also, what's a good brand of O2 sensor to buy off of Autozone? Which one should I get?

 

[jonridinhi]

Non foulers are suppost to be used on spark plugs to move them out of the cylinder. Our application is not what they are ment for. Basically with the aftermarket header there is no Cat so the second o2 sensor reads the same as the one and that pops a code. So you put 2 non foulers on it and limit the gases hitting it, it reads about right therefor clearing the code. Make sense? I will go look for the link to that diy.

What does the non fouler trick do? Would I be able to get a mechanic to do that? I have no experience with cars and repairing them, btw. Only thing I know how to do is an oil change and change the bulbs on my headlights, haha.

Also, what's a good brand of O2 sensor to buy off of Autozone? Which one should I get?

 

[jonridinhi]

http://www.mazdas247.com/forum/showthread.php?t=123634664&highlight=non+fouler+trick

Hope that helps.