p0420 code

[M@]

I just put in a K&N Drop in Air filter because I am too poor to buy an intake right now ! Yes I have two Bosch o2 sensors in it them seem to be doing fine right now. They are working I checked them the other day. Everything seems to be fine but my gas mileage it is like 15.1 but I have the Autolite 104s in them so Im pretty sure that is why it is like that otherwise it runs fine.

What do you mean that you checked them and they're working? The P0420 code can be a direct result of a sensor not working properly.

A poorly functioning O2 sensor is one of THE first places to look when tracking down poor mileage, so I would not be surprised in the slightest if BOTH Bosch sensors are not working as they ought to. Spark plugs are not the source of your poor mileage, almost guaranteed.

Get a new stock Delco for both sensors, or a new Denso for each, both are much much better quality than Bosch.

 

[PANDA]

I had bosch sensor DOA before, just buy a GM sensor its worth double the price.

 

[G_T_O]

ok ill look into it. Thanks!

 

[M@]

ok ill look into it. Thanks!

how did you conclude that the sensors were both working? Were you scanning/logging the thing, or...?

 

[G_T_O]

how did you conclude that the sensors were both working? Were you scanning/logging the thing, or...?

Ya i was scanning it the other day and both of the o2 sensors showed that they were working and functioning right.

 

[Alacran]

well the right way the sensors should work is the one front O2 is supposed to be switching faster than the O2 sensor. The rear O2 sensor should not be switching hardly at all if the cat is doing its job right.

Does that make sense?

Basically, if both sensors are switching equally as much or close to then the cat is busted.

 

[G_T_O]

well the right way the sensors should work is the one front O2 is supposed to be switching faster than the O2 sensor. The rear O2 sensor should not be switching hardly at all if the cat is doing its job right.

Does that make sense?

Basically, if both sensors are switching equally as much or close to then the cat is busted.

yes it makes sense and yes they are working perfectly find. There is nothing wrong with my car it was just the intake setup that I changed like M@ said it is most likely the IAC.