W205 new owner, nothing but problems

[striker20018]

New owner of a w205 17 plate coupe. Lovely car but have had nothing but bother since I got it. Start stop function hasn’t worked since day 1. It’s showing yellow with a line through it. Took it to a local garage and they’ve diagnosed the main battery as measuring low voltage so needs replaced. They’ve measured it at 9. Not experienced any dash warnings yet but In discussion with the trader I bought from to fix it under warranty but don’t sure how well that will go down. Question is, does having a low performing battery affect fuel performance? I’ve noticed it’s not been great. The car can be quite ‘shuddery’ and shakey when I go above 70mph and can feel the vibration from the footwell/accelerator pedal. Car has 4 new tyres so did think it could be that they need rebalanced, but then did wonder if the car was just lagging in general due to battery? I’m done in with the car and it’s only week 4. Had issues with AdBlue, washer jets and now this

 

[whitenemesis]

Many drivers disable the stop-start function so would be happy it doesn't function. Poor battery voltage will not affect the performance or mpg. The vibration is very likely to be wheel imbalance ..

 

[Teego]

Low battery will affect eco stop start function.

 

[MikeInWimbledon]

Reinforcing the two above, you seem to have a low battery, so if you can get a new one under warranty, just get one.

Juddering as you go past 70 is nowt to do with battery, much more likely to be wheel balancing and alignment, especially if all four have just had their tyres replaced. Again, get it addressed under warranty.

So you’ve had four issues all relating to poor owner maintenance and dealer prep. None of them sound that desperate, or long term problematic, really. These are great cars and shouldn’t be rejected in the windscreen washer jets are blocked or incorrectly adjusted.

 

[Bobby Dazzler]

New owner of a w205 17 plate coupe. Lovely car but have had nothing but bother since I got it. Start stop function hasn’t worked since day 1. It’s showing yellow with a line through it. Took it to a local garage and they’ve diagnosed the main battery as measuring low voltage so needs replaced. They’ve measured it at 9. Not experienced any dash warnings yet but In discussion with the trader I bought from to fix it under warranty but don’t sure how well that will go down. Question is, does having a low performing battery affect fuel performance? I’ve noticed it’s not been great. The car can be quite ‘shuddery’ and shakey when I go above 70mph and can feel the vibration from the footwell/accelerator pedal. Car has 4 new tyres so did think it could be that they need rebalanced, but then did wonder if the car was just lagging in general due to battery? I’m done in with the car and it’s only week 4. Had issues with AdBlue, washer jets and now this

Sorry to hear of your problems, none of them are ideal when buying a new car, however based upon what you have written, none of them sound like they are either expensive or difficult to resolve.

All are things that are surprisingly common and people are driving around with similar issues and are choosing to live with them rather than fix them, and the previous owner probably did the same.

The difference is you have bought the car from a trader and the trader has an obligation to make sure that the car is working in all respects, unless made clear prior you buying it.

According to the law, the seller must make all of these things right - or reimbursing you for the cost of you doing so - so don’t allow the seller to fob you off by saying that the warranty won’t cover it.

Good luck getting it sorted, and enjoy your new car. Oh and by the way

 

[markjay]

As above. The weak battery will only affect the Start/Stop function, nothing else. While the engine is running, electric power is provided by the alternator anyway, not by the battery (it's a bit more complicated than that, but essentially the weak batter won't cause issues while the engine is running).

regarding the vibration at speed, if it was down to front wheel balancing, I would expect it to be felt at the steering wheel. I would certainly have all 4 wheels balanced, but if this does not cure the problem, then I'd look also at suspension alignment, engine and transmission mounts, and drive shaft couplings.

Regarding AdBlue, unfortunately this is an unreliable system, and expensive to fix when it goes wrong. You say that the issue was fixed, but personally, still, I wouldn't want to own an MB car that has the AdBlue system unless the car has some sort of warranty to cover it. I would check cost of mechanical breakdown warranty cover, once the cover from the seller expires.

You also say "I’m done in with the car and it’s only week 4" - if you do want to reject the car because of the outstanding faults, be quick, because it's easier to this within the first 30 days.