ninsei

hi. got fault 0271 right side cam adjustment error. when i double click on it, DAS says do not replace sensor or solenoid, just clear the fault. but it keeps coming back. i would think the sensor is the first thing to replace.

Rudeney

DTC 0271 is one of the codes in the TSB that indicates camshaft senor magnet failure (Scenario 2):

http://benzbits.com/BalanceShaftTSB.pdf

Glyn M Ruck

+1 ~ I suggest replacing all 4 magnets while you are about it. They were redesigned. Star warns you not to replace the sensor. Only magnet.

ninsei

thx. just so we're talking about the same thing, anyone have a part number?

Rudeney

Here you go:

A272 051 01 77

(you need 4).

ninsei

Thanks, as always. I ordered 4 from germanautoparts.com (if you've never heard of them, good website, fast shipping), plus orings. Now, I'm hoping they're relatively easy to replace ;-). Looks like they are all in the front of the engine?

Rudeney

Yes, very easy. I think you may have to remove the position sensors to get the magenets out, but otherwise, it's just a few bolts and the R&R is done.

ninsei

thanks. WIS says have to drain coolant and remove oil/water separator to remove one of the left side ones. is that true (2007 clk 550)?

BTW i was wondering how this engine (which I'm liking more and more) did variable valve timing. have to read more about this. looks like these are solenoids not just magnets. they control oil flow to adjust the timing (somehow) of both the intake and exhaust camshafts. cool.

Rudeney

I don't believe you have to remove the thermostat on the M273. You will need to move the power steering fluid reservoir out of the way. Officially, you have to suction out fluid and disconnect it, but you may be able to just move it slightly and use a small wrench to get to the solenoid bolt behind it.

As for how the variable valve timing system works, basically, there is not a hard connection between the sprockets driven by the timing chain and the camshafts. Instead, each camshaft has a hydraulic clutch between it and the sprocket. The relative angle of that clutch can then be adjusted by the solenoids, which are controlled by the ECU. and those solenoids are really just electromagnets.

Glyn M Ruck

You can change them with a very slim spanner.