I completely rewired my 3.0i engine today. It took like 8 hours.
I had an SES from my oil temp sensor that did not go away even when I replaced the sensor. Plus, sometimes (I'm pre 2004) I would get random EML faults because of my harness. I would unplug a couple things, plug them back in, and everything was good.

Interestingly, I used a Euro spec RHD engine harness, which seemed to work fine, and since I got a real BMW part for $125, I think that was worth the chance.

So back to the main point: that was a bear. I took a few pics I can post. The TIS I had left out a couple of things.

I have no SES, and everything seems to be working as normal...except I have a battery light. I of course swung the steering wheel from lock to lock and it cleared the battery disconnect stuff, but the battery light itself is still on. The negative lead is nice and tight.

I think I may have switched up the two wires on the engine harness that go to the starter, but I would have thought that would have yeilded no starting. The other thing I thought of was my alternator plug is not in all the way.

Of course I had every wire for the motor off the car, so it could be anything. Overall I am pretty pleased though.

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2001 E53 3.0 5pd