As much as this has been discussed before, I'd like to get an updated opinion on the reliability of the GLK 250. In particular, are emissions problems to be expected with this car at some point, or was it just a small percentage of cars having issues with the DEF system. Are there any additional issues with owning one in California besides the smog check?

 

I've had the 250 since 2013, absolutely zero issues with emissions system, or any other issue for that matter. however, emissions problem is always in the back of my mind as I'm out of warranty!

Waiting to see if MB USA are going to do any action regarding the diesel 'scandal'.

 

Know that going into the purchase that these cars are high maintenance. Refilling DEF, using the correct oil, all services up to date. Using the incorrect oil will cause premature emissions failure. If they don't have service records, run!

My 2013 has gone through 2 NOX sensors, upstream 2x. I will never get rid of it.

 

Agreed: make sure services have been on schedule and by reputable shop. Beyond that, any used car will be an unknown, so plan on either paying an Indy to maintain it by the book ($$$$) or plan on investing in some tools, a quality scan tool, and buy the OEM parts to do maintenance and repairs yourself.

Avoid biodiesel if you can; common rail diesels don’t like it.

Top off DEF/AdBlue when notified, use the proper oils (229.51 or 229.52 MB spec, brand-agnostic), and drive it like you mean it. No *****footing, modern diesels hate that.

You’re likely to need a charge air hose sooner or later (read plenty available here), you may experience emissions related check engine lights, but that’s just the luck of the draw. Hopefully MB will offer a fix, extended warranty and/or buyback option at some point. Things seem to be headed that way.

Watch out for front brakes warping. A common thing on GLKs it seems, not specific to Bluetecs.

Otherwise, happy motoring. We’re at 101k miles and counting.

 

FYI emissions warranty I believe is 80,000 miles? DOT requirement.... is it not?

Supposed to cover any part on car that controls exhaust emission

I think it is in the fine fine Warranty print.

 

Differential pressure sensor and DPF replaced at 18k miles. 3 weeks in the shop.

 

No problems with my wife's 2015 GLK250 (grabbing a lump of wood as I type).
I do the maintenance myself and always use MB filters and Mobil1 5W30 ESP. I suspect that at least some emissions problems are caused by use of non-ESP oil which will choke the systems over time.
I've heard and read many times that city driving is a killer for modern diesel emission systems because they don't get sufficient chance to re-gen.
Your ideal car would be one with a verified service record using ESP oil and a car that has had regular highway trips. This complicates your search but should reduce that chance that you'll be walking into a nightmare.