MB718

Hi ya'll. I have a GLK-350 4matic. 2015 and took it to the shop to get the brakes done BUT because I also had a check engine light (which keeps going on and off every few days) I asked the mechanic to hook it up to read the code. This is what it said-- CAMSHAFT POSITION SENSOR - See image.

The car sometimes makes a rattling sound when I start it up. It comes from the catalytic converter area underneath. Low on funds at the moment and preparing to drive the car 6 hours up north soon. Wondering if anyone has any knowledge of this issue and if it's fine to drive for now? I was reading up on it and heard that it may have to do with the starter and that at some point if not repaired it will cause the starter not to work. Also read it could just be a broken sensor. But because of the noise I sometimes hear I assume it's not just a bad sensor.

Any thoughts would be appreciated.



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Odd Piggy

P0346 is a generic code showing a problem detected in the engine timing or the timing circuit. A Mercedes specific scanner is needed to see if there is more information.

How many miles are on your GLK?

The start up rattle could be the timing chain, camshaft adjuster, or chain tensioner. None of those failures are all that common on the M276 engine, but they have occurred, with the tensioner probably being most common.

I agree that it’s probably not the sensor, but I keep inexpensive Bosch sensors that I know are good in my shop to swap in before further diagnosis.

You did mention that the rattle sounds like it’s coming from the catalytic converter area. The monolithic converter elements can break if the exhaust system gets a sharp impact or the SUV was in an accident. I have seen this once in the last 20 years. On the outside chance that is the source, let the exhaust system cool to where it can be handled. If you have a rubber mallet, tap the exhaust pipe near the converter and listen for a rattle. If that’s it, it’s just a rattle that doesn’t affect anything whatsoever. But that isn’t the source of the trouble code.

I really wouldn’t want to take a GLK with a rattle and a trouble code on a 6 hour trip without further diagnosis. Worst case would be a timing chain failing or jumping timing which could turn a manageable repair into a destroyed engine.

MB718

thank you for the feedback. Very much appreciated. My car has 129k miles. It did have a minor front end accident before I bought it so maybe the rattling is caused by what you mentioned. But don’t think that would cause the engine light to go on would it?

Also hope any of the potential problems you mentioned don’t occur on my upcoming 6 hour trip

guess I will have to investigate further.

Odd Piggy

Just added my opinion to the original reply.

MB718

Do you have any idea what a repair like this would cost? Timing chain or belt.

I read up further after your comments about this potential issue and I agree it doesn’t sound like a good idea to drive 6 hours or at all.

Lastly, sometimes the sound doesn’t happen and the engine is not lit. When that happens does it mean the chain is working for the time being?

thanks again

Odd Piggy

You could probably get the timing chain replaced for $1500-$1800 at an independent shop.

Unfortunately, I don’t think that’s what is happening.

The ECU sets the P0346 code when it has seen the timing error 3 times in a row. Then if it sees 3 starts without the error, it turns the CEL off. If the timing error does not reoccur, then it was a random error and all is good. If it keeps coming back, then there is something wearing out that is on the verge of complete failure. That’s usually one of the camshaft adjusters. Your engine has 4.

Your symptoms exactly match what I had on my M271 engine, which is not at all similar to your M276, but both use camshaft adjusters. My failure occurred very early and Mercedes covered it under an extended warranty. I don’t think that is available for the M276.

You really need to have the situation diagnosed by a competent independent Mercedes or German car shop. The dealer will be exceptionally expensive. Then after you get an estimate of what is recommended, with details and components, post that here. We’re all sensitive to escalating costs right now. There may be ways to minimize the cost of this repair.

MB718

You said "unfortunately you don't think that what's happening" to a repair that could cost $1800. That worries me lol. I guess camshift adjusters would cost more to repair?

Either way I will find out soon enough. Hoping to take the car to a good shop this week and get to the bottom of it. Will definitely report back here with the estimate to help others.

You have been super helpful OP. Much appreciated.

calder-cay

Hmmm. I'm no doubt rwong [sic], but isn't there a voluntary recall for certain GLKs related to this, even for later years??

I'm not sure this recall is for the 4Matic, but my memory is always questionable.


​​​​​​https://mbworld.org/forums/glk-class-x204/883144-egt-sensors.html#post8917169

MB718

the only recall I know of was for the airbag.

Silver Shadow

Cam solenoids is a cheap repair. No big deal. I had mine done.

Odd Piggy

It could be less if it’s just the cam solenoids that have been mentioned. They’re inexpensive and not much labor.

My M271 cost about $3300 maybe 5 years ago for 2 cam adjusters, timing chain, and chain tensioner. That was indie shop invoice cost. Parts are not cheap and there’s lots of labor.

Keep us posted.

MB718

Ok thank you all. Will keep you posted.