E46 323i fuel trim P1188 and P1189

[bavareze]

Hello,

So ever since I got this 323i with 170k I had these two codes, plus other related codes like P0170, P0173, P0150. Car runs fine.

Reading the forum I learned this might be caused by faulty O2 sensors. So today I went to Autozone and purchased two Bosch Premium 13466 sensors. After installation, nothing really changed.

I looked into Live Data section with my scanner and I found out these figures:

I let the car idle and the values slowly go to:
STFT B1 27.3% and stays there, I assume it is maximum
O2S B1 0.035 V
STFT B2 27.3%
O2S B2 0.035

it idles just fine like this for about one minute, then changes by itself to:

STFT B1 0 (zero)
o2S B1 0.025 V
STFT B2 0 (zero)
o2s B2 0.025 V

Any help would be highly appreciated!

[bmwtech1]

Looks like by the 27% that the dme is trying to add fuel to compensate for a lean mixture, if it was negative it would be trying to take it away. More than likely you have a vacuum leak. I would check the black intake boot, both sections are know for splitting but the more common one is the one that connects to the throttle and idle valve, it usually rips at the little elbow that goes to the idle valve, if you can't see it reach your hand in there to the backside of that elbow and you will probably be able to put your finger right in there.

[bavareze]

I will check all that. Besides that, in the meantime the head gasket got blown. so I will have some fun soon! thanks for ideas!

[bmwtech1]

Once you get the cylinder head make sure you bring it to a machine shop and get it pressure tested and checked for cracks, there is nothing worse than putting a head gasket on and finding out that the head is warped or cracked.......trust me.

[WABMWTECH]

When you do that head job just pray the threads don't come out of the block

[witeshark]

Never use the old bolts, always get new ones.