I've a 2006 CLK250 Cab. with the infamous low serial number ( bad balance shaft sprocket) M272 engine. Recently, I replaced the Camshaft sensors and the CEL went out, but returned 2 starts later with the familiar code. Since the code refers to both the the cam and crank sensors, do I now need to replace the crank sensors?
BTW, either is a simple swap out.

You have a bad balance shaft.

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CENSORED due to not family friendly words

remove engine balance shaft comes out the rear about a 20 hr job, longer if its your first time 3 days, there is a kit sold , but you made need more gaskets etc , sealant coolant pulse wheels etc