Hi NAM!

I hope you guys can help me because I've been scratching my head over this one for the past couple of days. I recently had my wife's R50 up on the stands for some maintenance and all was fine when I handed it over to her. She drove to work, filled the tank (with premium), and came home only to tell me her MIL had come on and that the traction control indicator was on and wouldn't go off.

Now some background:
2006 R50, Manufactured 11/2005
Five speed manual
98,925 Miles on the odometer

Her car is approaching 100k miles and she was set to go out of town for a week, so I figured it was an optimal time for some maintenance/repairs.

Here's the list of services and parts:
Oil service (filter, drain & fill) - BMW/MINI synthetic 5w-30
Brake service (front rotors, pads, fluid flush & fill) - EBC Greenstuff DP21388, ATE Super Blue
SS brake line install (some scuffs and wear on the originals, and since I was flushing, figured what the hell) - BMMC1000CL
Engine air filter - MANN C2245
Cabin air filter - MANN CU4624
Serpentine belt replacement - Gates K060406/6PK1036
Inner CV boots (when I went in for the rotors, I noticed they both sides were torn) - Lobro GKN 304412
Inner CA ball joints - Lemforder 25385 02 009
Outer CA ball joints
New ignition wires - Kingsborne Firebraid 12-7000FB
New spark plugs - NGK Iridium IX, Standard heat range ZFR6FIX-11
New battery (hers was starting to fail when the outdoor temps started dropping) - Optima Red
Transmission fluid drain and fill with an LT-3 equivalent (according to my local independant MINI shop.) - BG Products #792 API GL-4 SynchroShift II 75W-80


Still pending:
Fuel filter replacement, I just didn't get to it before she needed it back.

After I was done, I scanned for errors and there were none. I then took it for a test drive then rescanned, and still nothing. The next day, the MIL was glowing. I did nothing engine side except replace the belt, plugs, and wires.

When I saw the 0340 code, I backprobed the camshaft sensor with my oscilloscope (grew up working on cars, fix electronics for a living) and saw that I was getting a correct waveform and a peak to peak voltage of about 4.75V. 1/2 duty cycle puts it just below the 2.5V spec for the sensor at idle, so I'm assuming the sensor is fine.

Since I don't have a breakout for the ECU cables, I'm trying to figure out a way to backprobe the crankshaft position sensor to verify that waveform, but its a pain to reach and have the engine still operable. I've only been able to access it by going into service mode, so my thought is of making a long probe that I can insert through the bottom of the car while it's up on ramps. Another option is I can take the crankshaft sensor from my project R53, but since it's not an easy swap, I'm trying to avoid it. Also, I'm getting tired of cannibalizing parts and funds. I want my 53 on the road as well!

As far as the TCS light goes, that's also a mystery. Of the past six or so start-ups, it's come on about 50% of the time and of course, will not shut off using the manual control. Could latent air in the brake lines cause this? The lines were thoroughly bled, or so I think they were. The brakes feel fine.

The car starts right up with no hesitation, idles smoothly, runs well as far as I can tell, but I can't get those codes to go away and as I mentioned, the TCS light comes on occasionally at start-up. It might be a little sluggish, but I honestly am not sure since I don't drive it that often and am used to my modified S. I'm also not convinced that that's just in my head since I know when these errors are thrown, the ECU shifts to a default map.

To top it off, my OBDII scanner died shortly after clearing the codes to see if they returned...they (or something else) did and now I'm out a scanner so I have no idea. I might have to run by an AutoZone and have them read them for me.

So, there you have it. Any suggestions? If the crankshaft position sensor is bad, what could have caused it to fail, and why now? If the issue lies in the timing, why? I don't see how the timing could have been affected by a simple belt / plug replacement. I'm at a loss. Please help!