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Discussion Starter · #1 ·
Maybe someone can help. My 2015 GLA 220D 4Matic has about 60K easy-driven miles.

Last week I went to reverse and got the error 'Reverse not possible: Consult workshop'. I drove it home, but it kept losing power, then gaining power. Nightmare.

Mercedes are talking a new gearbox/flywheel.
Independent opinion links it to a sensor issue.

Anyone had this issue?
 

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Yes, I had this issue on my 2015 GLA 250. Ended up needing a new transmission ($9,000.00). The power surge you’re experiencing sounds a lot like my issue. When driving it would only use the even numbered gears so it would wind out in first, skip second, hit the low end of third, skip four,……
After a few restarts, it would be fine, then act up again. Turns out something broke and chewed up the first “layshaft” (even numbered gears) of the dual clutch system.

After some fighting, MBUSA did help out with cost (about $7,000.00) as the car was only 200 miles and one month out of warranty. Had I been able to get it in to the dealer when I wanted, it would have been free, but no car should need a transmission at 50-60K miles.

It took the dealer about 2 months to get and install it (they gave me a loaner). Made me think twice about keeping the car, and I’m really hoping I’m wrong in your case.
 
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Discussion Starter · #3 ·
Yes, I had this issue on my 2015 GLA 250. Ended up needing a new transmission ($9,000.00). The power surge you’re experiencing sounds a lot like my issue. When driving it would only use the even numbered gears so it would wind out in first, skip second, hit the low end of third, skip four,……
After a few restarts, it would be fine, then act up again. Turns out something broke and chewed up the first “layshaft” (even numbered gears) of the dual clutch system.

After some fighting, MBUSA did help out with cost (about $7,000.00) as the car was only 200 miles and one month out of warranty. Had I been able to get it in to the dealer when I wanted, it would have been free, but no car should need a transmission at 50-60K miles.

It took the dealer about 2 months to get and install it (they gave me a loaner). Made me think twice about keeping the car, and I’m really hoping I’m wrong in your case.
Yeah that sounds like mine Nick, if it comes to it I can pickup a second box for 1K with a 3-month warranty.

But your absolutely right, an MB gearbox should last much longer than 60K!
 

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Porsche PDKs have a low failure rate but should they fail they cost over twice what the GLA DCT costs. And Porsche refuses to repair them. But over the last dozen years the primary problem has been isolated to a shift rod position sensor. No mechanical failures. Just electronic. And now a few different parties have reverse engineered that part and repair costs have dropped significantly.

And as we know, electronics fail on a bell curve that we are all susceptible to. I suspect we are seeing a similar problem to Porsche's problem. If the TCU (transmission control unit) can't sense that a shaft has moved it cannot select the gears in that shaft (either odd gears on one shaft or even gears on the other). So there are two options ...

1. Shut down the transmission (and car) completely.

2. Refuse to operate the clutch on the seemingly non responsive shaft.

The second option allows you to get home.

It sucks to have any failure. And with the amount of electronics in modern cars that are powered by a less than stable battery is amazing we don't have more problems.

And this brings up a point ... batteries become unstable. And an unstable power supply can wreak havoc with sensors. And this can cause phantom failures. I read and decipher codes first. But the battery is always suspect.
 

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But your absolutely right, an MB gearbox should last much longer than 60K!
[/QUOTE]
Again – really hope it’s not the issue with you. As Wayne smartly points out, get your main battery checked. If it’s the original, it’s likely dying. I recently replaced mine and before I did it threw all kinds of crazy codes – most regarding the transmission (which only has 20K miles on it). The “tell” for my battery was the eco start./stop no longer engaged, and I was also told that the main battery also fires the fluid pump for the transmission to sort of “pre-prime” it before going in gear, and if that doesn’t fire, well….here’s your code!
 

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Maybe someone can help. My 2015 GLA 220D 4Matic has about 60K easy-driven miles. Last week I went to reverse and got the error 'Reverse not possible: Consult workshop'. I drove it home, but it kept losing power, then gaining power. Nightmare. Mercedes are talking a new gearbox/flywheel. Independent opinion links it to a sensor issue. Anyone had this issue?
I have same model/year and recently started having the same issue but I never change the battery on my car since I’ve got the vehicle in 2018. I’m hoping mine is just a battery issue.
 

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2020 MB GLA250 4MATIC Avantgarde Edition
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Yes, I had this issue on my 2015 GLA 250. Ended up needing a new transmission ($9,000.00). The power surge you’re experiencing sounds a lot like my issue. When driving it would only use the even numbered gears so it would wind out in first, skip second, hit the low end of third, skip four,……
After a few restarts, it would be fine, then act up again. Turns out something broke and chewed up the first “layshaft” (even numbered gears) of the dual clutch system.

After some fighting, MBUSA did help out with cost (about $7,000.00) as the car was only 200 miles and one month out of warranty. Had I been able to get it in to the dealer when I wanted, it would have been free, but no car should need a transmission at 50-60K miles.

It took the dealer about 2 months to get and install it (they gave me a loaner). Made me think twice about keeping the car, and I’m really hoping I’m wrong in your case.
My father had that issue with a Ferrari California which was Ferrari's first DCT (also a 7 gear) and one of the first "mass produced" consumer cars with a modern DCT/F1 gearbox. The car was also skipping gears (can't recall if they were the even or odd ones) because one of the clutches or sensors had an issue. I also don't really remember what the cause or solution was, but it wasn't a big problem because no major parts or expense were required. Whatever was done was under warranty. IIRC, the problem was resolved with a quick diagnostic or went away on its own.

If I got hit with a $9000 repair quote a mile out of warranty, I'd probably lose my ****, sell the car as is right there and tell the GM that I won't get another car from that brand again. sounds drastic but I can't get my head around that, even if they "reduced" it to $7K.
 

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I have same model/year and recently started having the same issue but I never change the battery on my car since I’ve got the vehicle in 2018. I’m hoping mine is just a battery issue.
What year is your car and what is the odometer reading? How often is it driven? a lot of issues turn out to be electrical and are easily resolved by replacing or fully charging either of the car's batteries. Any aftermarket electronics that might be causing the issue? anything not powered through the 12V socket or a fuse tap at an authorized location are suspect by the dealer.

electrical issues are way cheaper and preferable to transmission swaps. all the best. are you booked in with your service centre?
 

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Actually, I found receipts where I did change my battery last May I did a full work up on my 🚘… Now I realize it’s gotta be something else, could be sensor issues, just mind blowing how many ppl have the same issues with ben, I work from home so I only drive it when I need to. When I travel to go vid family it’s normally 200 miles round trip. It’s scary because my car was throwing all those codes about collision and inoperative while I was in a local parking lot and the car went into reverse not possible and when I tried to break the car kept moving and eventually went into park.. I’m greatful I was not in busy traffic…

my car is 89;121 miles. I know Benz sets their cars when it reaches a certain miles you have to take it for service and I’m beyond that 87, 000 miles mark for that service.

I’ll post back Saturday when they provide their diagnosis.
 

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Year 2015 GLA 250 , I previously had C240 4 matic and I will never get anything 4 matic because that means certain parts are double in the vehicle and repairs are more costly been there done that. Benz can keep their 4 matics :(
 

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btw: A minor wordsmithing technicality my learned associate but Professors may grade on a "bell curve" whereas RMA/Logistics types rather deal in a "bathtub curve" (albeit an upside down one). This as most failures occur either early in a system's life ("infant mortality") or in older age (hence aggregate "womb to tomb" longevity). Again, just a technicality. "You say tomato ...." ;)

And yes, a marginal 12V power supply wreaks havoc with the myriad electronics in modern vehicles.
Porsche PDKs have a low failure rate but should they fail they cost over twice what the GLA DCT costs. And Porsche refuses to repair them. But over the last dozen years the primary problem has been isolated to a shift rod position sensor. No mechanical failures. Just electronic. And now a few different parties have reverse engineered that part and repair costs have dropped significantly.

And as we know, electronics fail on a bell curve that we are all susceptible to. I suspect we are seeing a similar problem to Porsche's problem. If the TCU (transmission control unit) can't sense that a shaft has moved it cannot select the gears in that shaft (either odd gears on one shaft or even gears on the other). So there are two options ...

1. Shut down the transmission (and car) completely.

2. Refuse to operate the clutch on the seemingly non responsive shaft.

The second option allows you to get home.

It sucks to have any failure. And with the amount of electronics in modern cars that are powered by a less than stable battery is amazing we don't have more problems.

And this brings up a point ... batteries become unstable. And an unstable power supply can wreak havoc with sensors. And this can cause phantom failures. I read and decipher codes first. But the battery is always suspect.
 

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Actually, I found receipts where I did change my battery last May I did a full work up on my 🚘… Now I realize it’s gotta be something else, could be sensor issues, just mind blowing how many ppl have the same issues with ben, I work from home so I only drive it when I need to. When I travel to go vid family it’s normally 200 miles round trip. It’s scary because my car was throwing all those codes about collision and inoperative while I was in a local parking lot and the car went into reverse not possible and when I tried to break the car kept moving and eventually went into park.. I’m greatful I was not in busy traffic…

my car is 89;121 miles. I know Benz sets their cars when it reaches a certain miles you have to take it for service and I’m beyond that 87, 000 miles mark for that service.

I’ll post back Saturday when they provide their diagnosis.
That’s really scary I’m glad nothing happened. Have the dealer do a voltage check anyways because if the battery failed and is causing the issue that should be under warranty. Since you don’t do a lot of driving, the battery probably discharges and recharges a lot more than most cars would. I also don’t drive much so I have a battery charger/maintainer for the car. Otherwise hopefully it’s a computer or sensor issue because that’s a lot cheaper than a radar.
 

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Huey is right to say ...

btw: A minor wordsmithing technicality my learned associate but Professors may grade on a "bell curve" whereas RMA/Logistics types rather deal in a "bathtub curve" (albeit an upside down one). This as most failures occur either early in a system's life ("infant mortality") or in older age (hence aggregate "womb to tomb" longevity). Again, just a technicality. "You say tomato ...." ;)

We always burned (actively operated at elevated temperatures) all of our controls for a minimum of 100 hours before shipping. The military determined that of all failures to occur in the first 5 years 95% would occur in the first 24 hours. Go 48 hours to catch 98%. A burn of 72 hours got you to 99%. And going 96 hours would catch 99.5% of all failures expected to occur in the first five years. 40 some years ago we saw infant mortality cause fall out.

But for the last 30 we had to debate the value of burning because as chips improved fallout went to zero. We kept the burn period for quality control and to insure the global dealer network that they should check their own work installing the systems before blaming the controls.

These days it just seems that electronic failures are more random and I'm no longer sure what type of curve represents reality!!!
 

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That’s really scary I’m glad nothing happened. Have the dealer do a voltage check anyways because if the battery failed and is causing the issue that should be under warranty. Since you don’t do a lot of driving, the battery probably discharges and recharges a lot more than most cars would. I also don’t drive much so I have a battery charger/maintainer for the car. Otherwise hopefully it’s a computer or sensor issue because that’s a lot cheaper than a radar.
Thank you! Ok will have them check it and will look into that battery charger. Right, other than that I have had no issues with the car. But I want to trade it for the GLC 300, haven't heard any complaints on them.
 

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Huey is right to say ...

btw: A minor wordsmithing technicality my learned associate but Professors may grade on a "bell curve" whereas RMA/Logistics types rather deal in a "bathtub curve" (albeit an upside down one). This as most failures occur either early in a system's life ("infant mortality") or in older age (hence aggregate "womb to tomb" longevity). Again, just a technicality. "You say tomato ...." ;)

We always burned (actively operated at elevated temperatures) all of our controls for a minimum of 100 hours before shipping. The military determined that of all failures to occur in the first 5 years 95% would occur in the first 24 hours. Go 48 hours to catch 98%. A burn of 72 hours got you to 99%. And going 96 hours would catch 99.5% of all failures expected to occur in the first five years. 40 some years ago we saw infant mortality cause fall out.

But for the last 30 we had to debate the value of burning because as chips improved fallout went to zero. We kept the burn period for quality control and to insure the global dealer network that they should check their own work installing the systems before blaming the controls.

These days it just seems that electronic failures are more random and I'm no longer sure what type of curve represents reality!!!
For sure, did not realize how much trouble these cars gave until I joined this forum looking if anyone else is experiencing what I have. Human safety is no longer a priority, just push out defective products make it look good on the outside and we can recall it later.
 

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Thank you! Ok will have them check it and will look into that battery charger. Right, other than that I have had no issues with the car. But I want to trade it for the GLC 300, haven't heard any complaints on them.
I’d wait until next year for the GLC, they just released the newest model in Europe so it will be in North America in the next 6 months-1 year.

For sure, did not realize how much trouble these cars gave until I joined this forum looking if anyone else is experiencing what I have. Human safety is no longer a priority, just push out defective products make it look good on the outside and we can recall it later.
Most of these cars are very solid, it’s an issue of aging parts and a relatively new platform that make things problematic at times
 

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will def be next year after first quarter and that’s true no issues until now. But talking to rep at Benz she said I might just need a computer reprogram. As she mentioned the least thing can trigger the sensor, she even mentioned as of late so many coming in for service for their gas cap. She said it was simple fixes related to how the gas gap is being put on and a reset had to be done for that to be fixed.
 

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Please be reminded that automotive forums exist primarily for folks to find resolution for their issues. As a result these types of posts can far outweigh the 'silent majority' positive experience with the vehicle. Also this GLA-dedicated forum has a relatively small membership compared to units sold since MY2015. There aren't many threads entitled "I have no issues with my GLA." Just a consideration.

We have two 2018 GLA250's (AWD north; FWD south). No issues at all to date with the more regularly used AWD.

The only issues with the FWD were the main 12V battery needing replacement at almost exactly one year post delivery (under warranty). Another such replacement was required a couple months ago (out of pocket). In fairness the second replacement was likely resultant of extended pandemic absence, despite it being on a quality battery tender and periodically started by garage personnel.
"Fun fact" - both batteries failed during three-year separated long roadtrips to DisneyWorld (and both with my son-in-law driving). "Happiest place on Earth???" :LOL:

Remarkably neither of the Aux batteries have needed replacement, despite all the problem posts on same you'll see here. So case in point. Perhaps I should start a thread "my 2018 Aux batteries are still viable." ;)
For sure, did not realize how much trouble these cars gave until I joined this forum looking if anyone else is experiencing what I have. Human safety is no longer a priority, just push out defective products make it look good on the outside and we can recall it later.
 
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