2003 z4 2.5l

[JoseSuchite]

The car had the throttle body replaced a few times, but it would stop working and necessitate another replacement. Granted they were always used. So eventually we bought a new one and that work for a bit until it stopped working and the stealership told me that the most probably cause is the engine wiring harness.

My question is, is there anything I can do to verify this fact, or is there anything else you guys recommend me to try before replacing it.

It is currently sputtering and in throttle failsafe mode. Very little power and barely moves.

[The Beastmaster]

If you went through a few throttle bodies, and they worked for awhile, then tanked, it definitely sounds like an electrical issue. Did you try and use the other throttle bodies again to see if they are somehow working again? First start with an OBD2 scan to see if there are any other issues. Then I would clear all of them, rescan, drive for awhile and see if codes pop up again. It could be a sensor that is bad, or the wiring harness has a short. That era of BMWs had some harness problems. If I were you, I would seek out a good old timer independent BMW specialist for a 2nd opinion. Dealerships are like body shops. They want to replace a part instead of repair it because it is faster, and gets the car in and out.

[JoseSuchite]

I didn't try the other throttle bodies again. As of right now the car won't move faster than 1 or 2 mph. I also read about the DME possibly being an issue, what do you think of that?

[BimmerBreaker]

What codes does the car have? BMW P codes specifically, which will be the letter P followed by four numbers

It is not uncommon for those MS45 DME's to fail - the throttle bodies on the M54 are very reliable, the engine harness does occasionally have issues.

[JoseSuchite]

I don't know of any codes appearing with a P in the car right now. There are ones that start with S.

I was wrong, the codes I've found are -
P1508
P1504
P1511
P1634