Greetings all. I recently purchased a 2005 X5, 4.4L to experiment with it as an off-road commuter (I live 8 miles in on a mostly unmaintained dirt road). It was know to have an active CEL, along with both valve covers leaking from multiple places. Before digging into the VCG replacement (which will be another write-up as much of the information in both my Bentley book and on the forums didn’t apply to Valvetronic equipped engines), I read the codes (Autoenginuity) and got:

P0392 Camshaft Position Sensor B Circuit Low Output (Bank 2)
P0024 Exhaust Camshaft Position Timing Over-Advanced (Bank 2)

Knowing that going in, I ordered new CPS all-around and proceeded to replacing the VCGs. Bank 1 (right) first as access was better, lots of experimenting with the Valvetronic motors (mine had no way to turn the shaft nor a plug to access the hex screw everyone says is there, totally sealed unit which I had no intention of drilling a hole in); even though mine “popped” as it was coming out, it stopped while going back in at the same place, so simply pressing it in while putting in the first hex screw returned the Valvetronic gear to exactly the same position it started in. So don’t panic when the motor pops out and DON’T screw it back in as often suggested, just push it down.

Note that the Valvetronic equipped engines have all 4 Camshaft Position Sensors at the REAR of the plastic valve covers, the upper is Intake and the lower Exhaust on each side. This is not mentioned at all in the X5 Bentley manual and is key to this fix!

Anyway, after completing & buttoning up Bank 1 (new plugs, both CPS replaced), I moved on to disassembling Bank 2 (left) which IMO was considerably more complex. Had to remove fuel rail, heater hoses, battery cable as well as the Valvetronic motor and then was able to barely maneuver it out.

While wiping off the head flange, I heard a metal tinkling noise when I reached the rear of the exhaust (lower) camshaft and realized the reluctor (the metal piece that the camshaft sensor “reads” which mounts on the end of the camshaft) was TOTALLY LOOSE, and spinning freely! The nut that’s supposed to hold it in place was laying in the head, fortunately it’s a bit larger than the oil galleries so it didn’t fall into the engine.

So basically, what the CPS was reading was just randomly bouncing around (or not moving at all) so it had no reference whatsoever. I panicked for a moment wondering how the reluctor was supposed to go back on but fortunately it has a keyway which fits a slot in the end of the camshaft. I took it all out, cleaned it up & reinstalled it with Loctite Red on the nut, which has a hex head, tightening it up as much as possible. The key was kind of beat-up, probably as a result of bouncing around, but still usable and the piece went back on just fine. Voila, no more CPS faults!

In 45+ years of working on vehicles I’ve never seen nor heard this mentioned as a cause of CPS faults and had I not lucked into it I’d have probably chased all the other possibilities without any luck whatsoever. So if you’ve been trying to trace CPS failures by replacing & swapping sensors, checking wiring, etc etc etc without any success, take a look to see if your reluctor has come loose. You can check it by simply pulling the CPS and using a screwdriver to see if the reluctor is rotating freely or perhaps has even fallen off the camshaft. You definitely have to remove the valve cover if that’s the case. I went back and checked- all the cams are the same design, so the reluctor could potentially come off any of them.

Hoping this helps get a few BMWs back on the road which are sidelined by the most obscure fault ever!

Sorry for no pics but am new to the forum and have to get my filesizes down. Coming soon...