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Discussion Starter · #21 ·
Temps are way too high for a 15min drive. Gearbox temp even more so, considering it doesn't heat up nearly as fast as the engine. For gearbox 85°C is of the highest I've seen and that's after several runs at 25-28°C ambient. For the engine I've seen 105°C again after several runs (spirited driving would be an understatement), but it only takes a few minutes of normal driving to drop back down to about 92°C. Our oil cooling system (cooler and whatever else is involved) is impressive, it's one of the things I'm mostly impressed with. If yours is failing, might explain why it's going into limp mode. How long does it take for the engine to cool back down to let's say 90°C?

So are the high temps the culprit of losing turbo power?
 

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So are the high temps the culprit of losing turbo power?
When the ECU "reads" high temperatures, instantly reduces car's power in order to protect it. The problem is to find what is causing these unusual high temperatures.
 

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There's just so many things that might be causing it, that's where I'd start looking. Gearbox temp specifically, which should heat up a lot slower. I've never seen anything above 86-87°C and like I said, that's after several consecutive runs, and you got 91°C in 15 mins. Same goes for the engine, you got 100°C in 15 mins which doesn't seem right. But I've seen 105°C (albeit after several runs, not 15 mins) and didn't notice any power loss so I doubt the engine temp is throwing it into limp mode. Now, whatever is the cause, it won't change the fact that both your temps are way too high for a 15min drive. Maybe it's a sensor and not the cooling system. It'd be helpful to check how long it takes for the engine to cool back down from 100°C to 90, while driving normally, at let's say 25°C ambient. No need to check how fast the gearbox cools down because that always takes a while. It both heats up and cools down a lot slower.
 

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2021 AMG CLA45 S
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In my country here we have summer all year long as we are near the equator, so during the day time the ambient temps can go as high as 40 degrees.

I've had both my engine and transmission temperature hovering over 90 degrees after spirited runs and the car doesn't cut power.

I've shared previously that I had a hidden error code which wasn't showing on the dash but an OBD scan revealed it. The engine isn't producing any power because the car is running on limp mode.

Rather than trying to guess and shooting in the dark, if you can get your car OBD scanned it will tell you whether there's anything wrong.

Sometimes, the check light only comes on after couple of engine on/off cycles.
 

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^ That's better advice than mine. Agreed.
 

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Hi,

Took delivery of my A45S (Designo Mountain Grey Magno A45 S AMG ) from Mercedes-Benz of Edinburgh East mid April 2021. Lovely car but only managed to put 1500 miles on the clock so far and mainly short journeys in Comfort. Early on I got a couple of "Transmission Errors". Nothing since but there is definately something odd going on with the transmission which means at times there seems to be no power or something doing a CTL-ALT-DEL!

Craig
It's not uncommon in C in my experience. Especially where I have done manual changes and then resort back to auto. The box seems to need time to think.
 
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