BigIce

Code P052E : Positive Crankcase Ventilation Regulator Valve Performance.
This seems to be a common problem with the C300. It was replaced under warranty at 44,000 km. And it's happened again, out of warranty at 74,000 km. It's not an easy fix.
I contacted the Mercedes dealer (Kingston, ON, Canada) via email and wrote about my concern that MB hasn't addressed this common issue. And to my surprise, the manager said he would contact the MB rep, and work for a solution. Mercedes to cover all the parts, and 50% of the labour costs. Which I was happy with, as the car was outside warranty. When I picked it up, they handed me a surprise $0 invoice, and said have a great day. If you find yourself in the same situation, it might be worth asking for a discount.

S18NGL

That's great news, BigIce. Obviously you have an excellent local dealer. We have just bought a 2017 C300, with about 53,000K Km on it, picked it up from M-B Brampton ON, went for a "spin" of about 90 km of mixed driving then, on the way home, we noticed the CE light had come on. Since the car was still under warranty, and brand new to us, I called the dealer the following day and arranged to have it picked up and investigated.

Turned out to be the same dreaded P052E71 issue, about which I of course knew nothing before we bought the car. Bottom line is that, with about three weeks' worth of factory warranty left, and a purchased upgrade to the Star Certified warranty, it was fixed by the dealer at no charge. I'm very glad we upgraded, because if this happens again, it'll be a couple of thousand dollars worth. The car is great, and we really love it; hope this is an isolated incident.

Interestingly enough, my average fuel consumption had been around 11 - 12 litres/100K, but when the car was returned from the dealer (all right, mostly highway miles, but still a reasonalble amount of city traffic), the clock was showing 6.7. The blocked valve clearly has an effect on power otput and therefore fuel economy, and this is obviously a huge improvement; we'll see how this progresses.

BigIce

Keep that warranty work order so you can find it S18NGL. Your future self might thank you.
I really like the car. And as long as MB owns up to these common/known issues. It's all good.
I hadn't even checked the km/100, but that makes sense. Enjoy!

whiteC3002016

i thought only 2015's and early 2016's had this issue?

S18NGL

Mine is definitely a 2017, but it probably depends on how long it took the factory to use up the old inventory of those valves. Apparently they've changed the design and added some sort of heating to it, so maybe that will deal with the sludge problem; heated oil is always more viscous than cold oil.

S18NGL

Excellent idea, BigIce, although it's something I do as a matter of course; I have service records in files on all the cars I've owned over the last 20 years or so. And we can always hope that M-B will continue to own up to, and deal with, these common issues. Reminds me of a GM car where the engine had to be removed in order to change or clean the spark plugs - I'm not sure whether the vehicle designers ever talk to the service managers!

A.Aashish

Hi Biglce,
I have same issue with my 2016 Mercedes C300. I have engine light with error code P052E: Positive Crankcase Ventilation Regulator Valve Performance.
When I called Mercedes they told me the repair cost including labour fee will be around $2500, which is alot. Is it possible for you to forward your email to Mercedes and their reply to take care of the parts and 50% labour cost. I can take my car to Kingston,ON if they can do it for free or as per email. I live in Toronto, ON.

BigIce

I don't think you need to go to Kingston. I asked my dealer, and they asked MB Canada who then made the offer.
I think the fact that this happened for the 2nd time on my car, and is a known issue helped me. All you can do is ask, if you're a regular customer, they might cut you a deal. If I recall the part isn't too expensive. But it's a big job. I said something like "This is a know issue on the C300. And to be truthful I expect MB to be better than this after replacing it 30,000km ago. Please let me know if you can help me out on the cost".
If they say no, ask around for a independent garage that specializes in Germans. Best of Luck!

A.Aashish

Thank you Biglce, I will try that.