johanssen

2008 S550, W221 body, (M273 motor w/ 5.5L V8). I have a very-stubborn/persistent 'p2090' code. This is a "circuit shorted to ground" fault code for the passenger-side exhaust camshaft position magnet. I have replaced all 4 cam magnets, all 4 cam sensors, inspected the cams to make sure they hit TDC at the same time (ruling out timing chain issues), and replaced the entire motor wiring harness. I have swapped around all the magnets and cam sensors to rule out any faulty ones. All connections are clean, none of the pins are bent, there's no obvious short to ground anywhere that I can see. The wiring harness was just replaced, with no resolution to the problem. The 2090 code will cancel out, but comes back right away each time. The car's in excellent condition, the engine oil is good, the engine runs like a top, there's no misfire codes, nor any other fault codes.
This one is driving me crazy. Any ideas?? Is there a trick to truly "canceling" this code?? I'm using the iCarsoft MBII scanner tool which is supposed to be the appropriate one for the car.
4/18/2023 PROBLEM HOPEFULLY SOLVED: Okay, I started over with fresh oil (30W) and filter, and thoroughly cleaned out the renegade camshaft adjuster w copious amounts of WD-40, and drove a few miles under load/acceleration conditions (to get the cam adjuster moving a bit) and the p2090 code hasn't returned. So.... evidently the oil was dirty after all, thus causing the adjuster to be 'sticky', thus throwing the "low signal" code.

MJ50

moved to W221 forum...

Shadly1

Did you get oil travel up the wiring harness all the way to the ECM? That is a symptom of a bad ECM.

BOTUS

I was going to say where oils leaks followed the harness all the way into ECU we do hear of quite a few that go pop - it can't be just oil as that shouldn't pop electrics... but other filth in the oil might. Pattern ECUs with more ability to tweak the map are becoming very affordable as are OEM Bosch units without the software

I get this is likely the wrong country - but the idea is there

https://www.obd2shop.co.uk/wholesale...-computer.html

BOTUS

or the more flexible option than OEM

https://www.obd2shop.co.uk/wholesale...tag-v7020.html

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konigstiger

https://www.obd-codes.com/p2090

johanssen

PROBLEM HOPEFULLY SOLVED: Okay, I started over with fresh oil (30W) and filter, and thoroughly cleaned out the renegade camshaft adjuster w copious amounts of WD-40, and drove a few miles under high load/acceleration conditions (to get the cam adjuster moving a bit) and the p2090 code hasn't returned. So.... evidently the oil was dirty after all, thus causing the adjuster to be 'sticky', thus throwing the "low signal" code.
Thanks to everyone for their comments/input

Minh

this problem is would very easy for diagnostic if you have Picosope: check PWM snet by ECU to camshaft magnet and check pulse signal generated by camshaft sensors.

BOTUS

if one uses search and adds a query to a very similar or ideally one of many identical topics - we all get to learn more and support each others knowledge far better - check a document in this thread I found from years back about why there's supposed to be little extra on the loom to the sensors

https://mbworld.org/forums/s-class-w...ml#post8761088