Steering Assist, Lane Keep Assist Failures
 

My 2019 C300 Cab has the Driver Assist package (997) which includes Active Steering Assist and Active Lane Keeping Assist, among other "assist" features. When Lane Keep assist is on, I sometimes get a warning (wheel pulsation or visual, or both), when I cross a lane marking, and sometimes I don't. To confirm the intermittent failure, I try to eliminate variables and always ensure I am inside marked lanes on both sides of the vehicle, and also not in intersections where the lane markings typically don't exist. Lane Keep Assist failure (no warning) occurs often.

With Lane Keep and also Steering Assist on, (along with cruise control), the vehicle weaves noticeably from one side of the lane to the other. Happens on surface streets as well as freeways, always in well-marked lanes. Sometimes vehicle will even cross into an adjacent lane. If I was driving like that (without the electronic features), I would be pulled over for erratic driving. Steering Assist failure occurs often.

I brought the car in for a seat belt recall and had the dealer Service check everything, and of course they said it's all working fine, even with a road test. Mechanic tried attributing failures to me not having the features turned on (of course they were turned off when I brought the car in because since they don't work, I don't use them). I asked which road(s) they use for road tests and drove them a few times myself and the Lane keep and Steering Assist both failed.

I brought the car in again and did a road test with a "shop foreman" and everything failed (intermittently) for him also, (he grabbed the steering wheel more than a few times because he feared the car would go off the road). However, he got another 2019 C300 Cab from the lot and we drove it and it had the same problems, although I don't think quite as severe (unscientific). So he says the car/functions are "working as designed". I said anyone would be out of their mind if they accepted that Lane Keep assist doesn't keep you in your lane or warn you if you stray, or accepted that Steering Assist would weave from side-to-side, occasionally departing the lane, and asked that he report the problems to Mercedes Marketing, Engineering, Design, or whoever, but he said they "have no channels to report those things". Seriously?? I asked to speak to the Service Director, who essentially gave me the same stories, (working as designed; can't report to anybody), and that I should contact M-B Customer Service.

This is the first Mercedes I ever owned, and priced at the top end of a C-class, and I must say at this point the dealer seems to be just as bad as any other car brand dealer I have ever dealt with, and deserving of the bad stories car dealers always get. I will pursue the Mercedes Customer Service route, but reading online stories about others contacting Mercedes Corp. with significant car issues, I'm not hopeful. My reason for posting this is to ask if anyone else with a late-model Mercedes with these Assist features has had similar problems and if so, has had better results with solutions.

Update: 1st dealer service (Foothill Ranch, CA) uploaded my ECM (computer) data for someone in M-B Land to analyze. After 3 weeks of hearing nothing I inquired and was told "no errors found", to which I responded that errors or not, the functions are not performing as intended, and it seems to be a design flaw, however dealer insists "nothing more they can do". Called M-B Customer Service who also says "nothing they can do either as they rely on dealer for direction". So if dealer decides they do not want to pursue a problem, it will just be ignored? Apparently so. Is this what the M-B slogan "the best or nothing" means?? Frustrated, I decided to try another dealer, but this time I asked to have the shop foreman ride with me before leaving the car to be checked. Foreman admitted he observed exact symptoms I was describing as we drove, and said he would check it out. Next day "service advisor" and foreman explained a software update was done which foreman thinks improved the problems. I drove the car a few days and reported back the Steering Assist was significantly improved, as now it stays in the center of the lane most of the time, however (1) it seems to "forget" its position occasionally and move to the left, then right (or vice versa) to recalculate back to the center; (2) It now also occasionally "hugs" the left lane marking, virtually on top of it, to the extent other drivers move away from me thinking I am about to cross into their lane; and (3) It now frequently thinks I have removed my hands from the steering wheel (presenting the red warning indicator), even though my hands have not left the wheel. Also, (4) second problem, Lane Keep Assist, still is not working at all; i.e. no audio/visual/physical warnings and no bringing car back into lane.