Hi all, I just wanted to give a heads up on the Mercedes C300 2015 model. For the better part of the year my engine has felt a hesitation. I have gone in several times complaining about it to the local dealership. Not once over the course have they offered to show me the results of the diagnostics exam. Nor did I think to ask for it.

Last year they change the spark plugs and they said it was part of the 50,000 mile check up And done based on me stating that I felt like the engine wasn’t “tight”. I thought that everything was going to be fine and that it was just spark plugs. But the next time I need to have an oil change at the 60,000 mile mark I took it to a third-party ( asit was cheaper going to someone else than Mercedes to get an oil change) to have it done and they ran a diagnostic as I told them that The engine didn’t feel quite right and could they do a tuneup. I gave them the same symptoms- that the engine just didn’t feel tight. Given I have had an extended warranty on the car, I have taken it in to the dealership to keep up with any items that could possibly be taken care of under the warranty, and I always get a loaner vehicle to use while the car is in the shop. I have been back to the shop a lot so I have driven a lot Of loaner cars. So I know what it feels like when the engine on my car is not as tight as the engine of new Mercedes. Of which when I state that to the dealership they dismiss my statements)

The third-party mechanic showed me the results of the diagnostics , he showed me that the engine fault tripped during the diagnostic. And he showed me the results . He told me I need to take it back to Mercedes because there’s something going to happen to my engine. He gave me a copy of the diagnostics and he told me to show Mercedes. He also told me that Mercedes normally would never allow me to see the diagnostics of the car. I went back to Mercedes with a copy of the diagnostic report from third-party mechanic in hand and told him of my concerns. They asked if an engine fault light had come on of which I said no, I said the engine just didn’t feel tight and the diagnostic from the third-party showed that an issue with the engine was looming and I needed them to take care of it.

They took the car ran a diagnostic and stated that no-fault came up on their diagnostic report. I asked to see a copy of the report, And they stated it was against company policy to let me see the copy of the diagnostics. I found this to be very troubling and given I had a copy of a diagnostic report from a third-party I felt They were not being honorable. It seem to me as if Mercedes was trying to not honor a warranty that I had and was not going to do anything until there was a check engine light visible to me.

The dealership stated that the third party mechanic had cleared the fault and unless a fault had tripped on their diagnostics there was nothing they could do. That said, they still didn’t allow me to see the diagnostic report so is my word against theirs. Now, six months had passed and the pandemic hit. The other day my windshield wiper stopped working on one side - it just stopped moving. So I took up the car to have it be checked out about the windshield wiper and my son stated that in the morning the car sounded rough In idle and from a cold start - It was making a noise in the early morning that it sounded rough, and that I should ask them about it.

This time I told them about it - I asked for a diagnostic to be run, they said it’d be $225 for that to be done and if there was a covered issue the cost would go away. They also asked if a check engine light came on and I said no. This time they came back and stated that the noise was coming from the Pistons and possibly my brakes too and that the extended warranty covered changing pistons the engine and transmission mount as well. The brakes however were not covered. Given I had the extended warranty this large ticket item was covered. That said, if I had not made a big deal about it to the dealership About them not showing me the diagnostics, I don’t think they would ever fixed the car Until the check engine light would come on. So I am just putting it out there that all Mercedes owners should be requesting a copy of the diagnostic reports and making an issue if they refuse. Because If there is no issue with the car they should have no issue with showing us a diagnostic report. There should be nothing to hide. I think we should all make an issue about it and that it should be mandated that they are transparent to the customers. There are far too many owners complaining of the engine going out and if owners were Shown the diagnostic reports when we take the cars in we could know if there is a pending issue coming up.

So the moral to the story is start asking for the diagnostic reports on your cars every time you take it in for service and if they refuse- make an issue. If there is nothing wrong with your car the diagnostic report that they print out should show no issues. It doesn’t mean that no report exists.

If an engine goes out and you have been refused a copy of your diagnostic report then I think there is grounds for a class action. There are certainly enough people on this forum complaining of pistons goping out at 65k Also be sure that when you go in for work on the car any complaints are listed in their computer and on the paperwork given to you . You want a paper trail. I think they are deliberately vague on listing complaints in writing so they have an out.

Also , always get the extended warranty on the car or any for that matter. It’s worth spending $2k on the warranty if you get hit with mechanical issues after it expires. This job could easily have been $10k - thankfully it was covered- but it also took me being a squeaky wheel with the dealership . Those other issues would have been very expensive as well. They could have sent me on my way until the engine light came on or until it died - they did the right thing by fixing it.

In owning the car for since 2017 , it’s been in and out of the dealership at least 6x with issues : seat head rest rattled, ( they had to replace the entire seat) interior paint chipping off , sunroof came off hinges and wouldn’t close, and the engine not feeling tight, a rough noise, hesitation in accelerating. I purchased a used car. In 2 - 3 years without an extended warranty I would have been out thousands of dollars by now, if not for the extended warranty. I’m hoping the car is going to be perfect now, but I fear as soon as my extended warranty is done I’m going to be car shopping - I’ve owned a Yukon and a Honda and they have each gone over 200k miles without significant issues. This Benz though is expensive to maintain without a warranty. The used car cost $40k and since then I’d have spent at least $20k given all the issues I have encountered if I didn’t have the extended warranty.

keep your ears open and be a squeaky wheel .

 

The early W205s were known to have piston issues, but I understand the dealership not really understanding what "engine doesn't feel tight" means. In this context with your explanation, now that you know it was piston related, it makes sense. But if someone had just said that to me I would have been like

A Mercedes was always going to cost more than a Honda or a GMC to maintain, that should not have been a surprise.

 

I will only buy a Benz as a CPO. Warranty is almost unlimited on them

 

Really? how come? Mine is a CPO, but was brought from USA to Europe. Does mine also has warranty?

 

I just got my 2017 c300 coupe Saturday from a dealer my dad deals a lot with so they hooked me up. But they were explaining the new CPO warranties are pretty much unlimited mileage now. If i have any issues they'll take care of me even if out of warranty but thats cus of my relationship with the dealer. Warranty is still pretty much unlimited.

 

My 2016 was purchased CPO April 2019 with 17k on the odometer. I thought that the CPO expired one year after the original warranty. Are you saying that my CPO is unlimited?

 

CPO adds 2 years of warranty up to 120,000 kms in Canada.
It is definitely not unlimited.

I have had pistons, control arms and front axles replaced under this program.
There is a very small deductible for each claim of $50.

 

Besides CPO, I buy the 2 year warranty extension. It paid off for me so far every time, especially with the 27x engines