About two weeks ago my brother and I installed my invidia catted dp, g200, and invidia uppipe (bung sealed). we flashed with a stage 2 map. shortly after I threw a cel: p1153, which is the front o2 (a/f) sensor (high). i looked around and found that maybe the o2 sensor was damaged. needless to say I went and bought a brand new one to replace. after a short drive with the new o2 sensor the same code came on. we checked for blown fuse and all wires. everything was fine. we decided to take everything apart and check for leaks. we found that the flange on the uppipe was bent and it was obvious that it was leaking due to the black spots on the gaskets. we had the flange machined flat. reinstalled everything, went for a short drive and the same cel came on. we checked again for leaks, not sure but decided to take everything apart and replaced all gaskets (crosspipe, uppipes, dp). went for a short drive and still the same code. any ideas? any help would be appreciated and sorry for the long story, but we have tried everything we can find on the related threads. thanks. car is 05 sti.
Well if you are getting that code, it means that the ECU is trying to dump in extra fuel meaing that it is either thinking the car is running lean during closed loop (or it actually is running lean). Check for any leaks between the MAF and all the way up to the throttle body. Its pretty common to get a leak at the turbo/turbo inlet joint that will cause a vacuum leak.
I can't agree more. OP- Check this connection first. Totally remove the worm clamp and feel around this connection with your hands. Make sure you check all the way around. most of the time they will rip underneath and towards the IC. Also, not a bad idea to use T-bolt clamps at that connection.
^correct...hopefully. so we were thinking...the uppipe was damaged in the first place but we didn't realize it and installed it anyways. since it was leaking at the flange, that throws the ecu off, which lead it to dump more fuel (?). this increased fuel eventually damaged the first sensor. now we thought it was a bad o2 sensor so i bought a new one to put in, still not checking the uppipe. ran the new one for a good 40 min on the highway (to the monticello meet) until the cel came back on, new o2 sensor was probably fried now. frustrated, we took everything apart and realized the uppipe leak. fixed that, reinstalled everything, still not realizing that the new o2 sensor was probably fried already. of course, problem persisted and we kept thinking it was due to a leak because the o2 sensor was new. until we checked with nuke and the log was fine. decided to take the chance of borrowing an o2 sensor to put in...and problem solved. so far so good. thanks to all the helpful advice guys. special thanks to nuke and vanddelor. now i have to go spend another 170 for a new o2 sensor. sigh.
Check rockauto.com - it is cheaper there if you can wait. Not to take anything away from the good folks at the dealership. I am fighting a similar situation and that maybe my next step.
Perhaps you shouldn't listen to me. This is my first Subaru, am an automotive newbie, read NASIOC and listen to 16 year olds (and Chet.) Do speak pretty good engrish though.
