jcresset

Hi, i've got these codes on my 8. My CEL comes up, just a couple of miles after I've deleted the codes.

I bought a rear ebay o2 sensor, beacause my first had slow response, these codes came after I changed the sensor,

I've got a racing manifold, stock catalytic converter and catback exhaust, Im out of clues whats wrong?

I dont feel any power loss, and the fuel consumption is OK.

RIWWP

iTrader: (2)

P2096 - Target A/F feedback system too lean
P2270 - Rear HO2S signal stuck lean

2270 suggests that you likely bought the wrong sensor from ebay if it is a new one in there. Try going through Mazmart.

2096 is thrown when your fuel trims are maxed out at +25% and it is still showing as lean. These are driven from the front O2, not the rear O2, though it uses the rear O2 as a check and balance to try to determine if the front O2 is acting up. So either A) Your rear O2 is telling the ECU that your front O2 can't be trusted and is forcing everything way lean, or B) you have a problem where the MAF isn't reading all of the air that is going into the engine, either due to fouling or because of a large vacuum leak. Not feeling any power loss suggests B, since getting 25% more fuel would certainly be a noticeable power loss and mileage loss if it was just a sensor reading incorrectly.

Get a bluetooth OBD2 adapter, pair it with your smartphone, download an OBD2 app (Torque is best for Android), clean your ESS and MAF, reset your fuel trims, and then see what your AFRs and fuel trims are reading. If it seems like a vacuum leak, go find it. Otherwise, replace the rear O2 with a proper one and reset the fuel trims, and monitor AFRs and fuel trims. If still having problems, replace the front O2, reset, and monitor.

jcresset

I cleaned my Maf sensor, so it Isnt that, Is there a common place where it can be a vacum leak, beacuse it idles a little rough, the same symptom I had on my old crappy volvo, I've ordered a new catalyc converter beacuse parts have loosened within the cat.

RIWWP

iTrader: (2)

A vacuum leak is anywhere that the engine can draw air in that is after the MAF, so there are literally a few dozen places it could be. There are many methods for finding a vacuum leak, but the only 'fool proof' one is to take the car to a shop and have the intake track smoke tested. A leak that big should be obvious however, like the lower intake manifold nipples missing, the accordion clamps loose, a vacuum line disconnected, etc...

jcresset

Found the problem, one of the hoses right after the MAF sensor :-)

RIWWP

iTrader: (2)

Good!

Make sure to reset the fuel trims, or you will be suddenly WAY rich until the ECU can correct it back down.

jcresset

Still have the p2270 stuck lean rear o2 sensor, but that will be fixed when i've got the sensor from mazda :-)