i have ultimate racing test pipe. and extended o2 sensor wires are in good shape
i got no cel in about 5 months after i put test pipe.
now it keeps throwing a cel on me....

anyone know what the problem is? input voltage of o2 sensor (after cat) reading high

dont tell me i need new ECU.

 

bump for help

 

the CEL says that the input from the second O2 is reading high? replace the O2 sensor then.

 

you sure?

 

bump for help

 

h
elp

 

Mine is reading low... I'm sure we ****ered it up some how... looks like we're gonna have to bay the bill on this one.

 

I have both high and low voltage on the front O2 sensor. Even got a lean code but I was running rich as hell at the track. Turned off the CEL, drove for 3, 20min sessions... no CEL. Got on the freeway, cruised to 60mph.. CEL.
I got over 30K miles on the car. The car drives fine and other than the CEL everything seems fine. Will be changing the O2 sensor soon.

 

i think i m running rich too.,,,cause im running methanol....
u think rich condition will damage the o2 sensor?
i got also over 30k miles on the car

 

I would assume that running rich all these miles might have fouled the front O2 sensor on my car. I have the mail-in dynoflash for about a year now.. consistently rich.. but the car runs fine.

 

You are probably running a P0138 code.
I was running the same code and I have the same Ultimate Racing test pipe.

I posted a thread on EvoM about this and got very little feedback except people saying the O2 sensor is bad or the wiring is bad.

Which way do you have the test pipe facing? I have to flip mine as the bung is facing down, I've heard that condensation builds up in the oxygen bung which isn't good for the O2 sensor itself.

I would first find out what kind of voltages your are running from the rear O2 sensor while running. I found that my rear O2 sensor iterates from about 0.680 - 0.700 at idle.

Running rich will damage the oxygen sensor over time but you would think that the oxygen bung will keep the sensor away from the direct stream of rich exhaust.

 

liljaponboy---------did u replace o2 sensor? and got rid of the cel?

and where is the cheapest place u can get for o2 sensor? are the before and after the cat o2 sensors are the same? thanks~

 

I'm still fight with this issue...well kind of.

I have to do some more testing however, my CEL went away.
The same thing happened when i had to redo my wiring when the solders came loose, the CEL took awhile to go away.

My next steps are to do some hard driving to see if I can trigger it again. Also to flip around the test pipe so that the oxygen bung is not facing downward.

If you want an OEM oxygen sensor then www.mitsubishiparts.net or www.mitsubishiparts.com are places where you can buy them.

There are also places that sell the aftermarket sensors that are not OEM but fit the Evo.