P0173 & P1189 Codes - My solution

[SunzOut]

I started getting these in the late spring on the S52 M Coupe

P0173 Fuel Trim Malfunction (Bank 2)

P1189 Fuel Control Bank 2 - Sensor 1

A lot of on-line solutions revolve around air leaks or Vacuum leaks on the Intake side, and I did find a large tear on the intake elbow and thought that was the cause. But the codes kept coming back.

I swapped most of the "Plumbing" related to Vacuum side (Idle valve, oil separator, hoses etc) and checked the various vacuum lines running to other components (like fuel regulator). No change.

Finally did the Pre-cat O2 sensor for Bank 2 and that did the trick. Purchased a Bosch 13884

http://www.rockauto.com/en/parts/bos...2)+sensor,5132

[macelius]

I started getting these in the late spring on the S52 M Coupe

P0173 Fuel Trim Malfunction (Bank 2)

P1189 Fuel Control Bank 2 - Sensor 1

A lot of on-line solutions revolve around air leaks or Vacuum leaks on the Intake side, and I did find a large tear on the intake elbow and thought that was the cause. But the codes kept coming back.

I swapped most of the "Plumbing" related to Vacuum side (Idle valve, oil separator, hoses etc) and checked the various vacuum lines running to other components (like fuel regulator). No change.

Finally did the Pre-cat O2 sensor for Bank 2 and that did the trick. Purchased a Bosch 13884

http://www.rockauto.com/en/parts/bos...2)+sensor,5132

Thanks for posting, having the same two codes after headgasket+head work+m50 manifold swap+ASC, SAP, and CCV delete. Can't find an air leak, but suspect o2 since one of them would occasionally pop an out of range code before the gasket went, but i figured that might have been because of burning coolant in #5 (or was it #4). Injectors are kind of loud too and the tip of #5 looked dark from all the gunk that was getting sucked right through the ccv and down that runner, but didn't get to rebuilding them (or even have time to clean them out) while the car was coming back together so probably good idea to address that now anyway.

Update: Pair of new NTK sensors (OEM, same as Bosch) solved the problem, and really woke the fueling system up. Throttle response is greatly improved, also seeing an improvement in fuel economy. Those 200k sensors must have been getting really lazy.