Check engine light came on

2012 MERCEDES BENZ C250

180,000 MILES • 4 CYL • TURBO • AUTOMATIC

DSALAS817

MEMBER
2 POSTS
FOLLOW

Check engine light came on and it hooked it up to a computer turned out to be the camshaft position sensor. i replaced them both to no avail and the light came back on. took it a mechanic and said the light could be from loose timing chain and the sensor not reading right. plus the chain was noticeably loose when i turned the car on. i could hear it. so i replaced that and new tensioner as well. but now the light is still on and i am getting a subtle constant rattle from the engine. I do not know what I am to do now.

Dec 20, 2018 at 4:53 PM

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JACOBANDNICKOLAS

AUTOMOTIVE REPAIR CONTRIBUTOR
110,190 POSTS

Hi and thanks for using 2CarPros.

Did you replace the timing chain? Also, can you provide the codes that you are getting?

Thanks,
Joe

Dec 20, 2018 at 6:10 PM

DSALAS817

MEMBER
2 POSTS

Yes, I have replaced it. Code p0340.

Dec 20, 2018 at 7:14 PM

JACOBANDNICKOLAS

AUTOMOTIVE REPAIR CONTRIBUTOR
110,190 POSTS

Welcome back:

If the same code still is coming up, I question if the timing is exact or if there is an issue with the tension-er or one of the cam adjusters. What I suggest is to recheck timing to start. I attached pictures below for you to review. Please confirm that the correct mark was used for timing on the cam. Also, reconfirm that the tension-er is working properly. If you are hearing noise, I suspect either the chain has come loose, the tension-er has failed, the rail is bad, or something is loose on the cam adjusters. If the any of the things I mentioned has failed, it will set a camshaft position sensor code.

Let me know what you find.

Joe

Images (Click to enlarge)

Dec 21, 2018 at 4:57 PM