Antlane90

my evo 9 is running rich before i had bad o2 sensors i replaced them im still getting the error code of a bad o2 sensor does anyone know what it can be

eliminator 429

iTrader: (1)

More information is needed for us to help. Have you done any modifications to your car lately? You may need a retune if you did.

Antlane90

no i just have basics dont cold air exhausts headers and upper and lower intercooler piping

evo8dreamcar

iTrader: (15)

Have someone read the readings from the o2 sensors. Could be a cat also.

Antlane90

ok thank but if it was the cat wouldnt it be the rear sensor the code pulling up is the upper sensor

Heezayx

iTrader: (1)

Have you done a boost leak test? if not you should because that could be the reason why your running rich... i had a huge boost leak and i was running super rich. try leaning your MAF sensor too

impact blue

iTrader: (1)

You have to make sure its an oem sensor not one from pepboys or over the counter or a used one. Also make sure that you check for boostleaks too that will make the car run like crap like Heezayx said. Then once al of that is done give it a tune up and then get it tuned. If you have a check engine light whatever its asking for get it fixed.

Svendiesel

iTrader: (25)

Check for boost/vacuum leaks.