Start/Stop Function Disable Over a Certain Temperature?
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Senior Member
Joined: May 2015
Posts: 253
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From: Scottsdale, AZ
2017 AMG GTS
Start/Stop Function Disable Over a Certain Temperature?
Hi, my start/stop function basically never activates. On the rare occasion that it does there doesn't seem to be any real reason as to why. I live in AZ where it's currently always over 100, but even when it's in the 90's, the start/stop still rarely activate. Is there an outside ambient temp that it is set to no longer activate past? Yes, it's on and I use comfort mode 95% of the time lol. 2017 GTS. Thanks.
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Joined: Apr 2019
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From: Scottsdale AZ
2015 CLS 550 2015 ML 400 Previous 2020 GLB 250 2019 A 220 2005 ML 350 1989 300 E 2001 SL 500
Hi, my start/stop function basically never activates. On the rare occasion that it does there doesn't seem to be any real reason as to why. I live in AZ where it's currently always over 100, but even when it's in the 90's, the start/stop still rarely activate. Is there an outside ambient temp that it is set to no longer activate past? Yes, it's on and I use comfort mode 95% of the time lol. 2017 GTS. Thanks.
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Joined: Oct 2020
Posts: 1,184
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From: Arizona
Bentley Continental GT; AMG GT
From the Op Man:
The ECO start/stop function switches the engine off automatically if:
the ECO start/stop function is activated (green light must be lit on the button)
and you brake the vehicle to a standstill in transmission position D (And only in comfort mode)
The ECO start/stop function is operational when:
the indicator lamp in the ECO button is lit green.
the outside temperature and the atmospheric air pressure is within the range that is suitable for the system. Big reason in PHX in the summer
the engine and the transmission are at a sufficient temperature for the ECO start/stop function.
the set temperature for the vehicle interior has been reached
the battery is sufficiently charged. Probably the biggest one, BC after a few years of normal use, the average battery won't charge enough to support this feature.
the system detects that the windshield is not fogged up when the air-conditioning system is switched on.
the hood is closed.
the driver's door is closed and the driver's seat belt is fastened.
The ECO start/stop function switches the engine off automatically if:
the ECO start/stop function is activated (green light must be lit on the button)
and you brake the vehicle to a standstill in transmission position D (And only in comfort mode)
The ECO start/stop function is operational when:
the indicator lamp in the ECO button is lit green.
the outside temperature and the atmospheric air pressure is within the range that is suitable for the system. Big reason in PHX in the summer
the engine and the transmission are at a sufficient temperature for the ECO start/stop function.
the set temperature for the vehicle interior has been reached
the battery is sufficiently charged. Probably the biggest one, BC after a few years of normal use, the average battery won't charge enough to support this feature.
the system detects that the windshield is not fogged up when the air-conditioning system is switched on.
the hood is closed.
the driver's door is closed and the driver's seat belt is fastened.
Out Of Control!!
Joined: Nov 2018
Posts: 11,458
Likes: 5,353
From: San Francisco Bay Area
2019 C63CS
Yes, there are several parameters that go into the decision of when to stop the engine. One of the main parameters is cabin temperature. If the AC is working overtime to keep you comfortable, the engine won't stop as otherwise the cabin temperature would rise quickly. It's a pretty misplaced feature on an AMG frankly. I turn it off first thing after starting the engine. When it's on, it often stops the engine just to restart it again a few seconds later resulting in increased fuel consumption and unnecessary wear. The engine has to be off for about 7 seconds to really save fuel, but with everything that's going on it doesn't seem all that effective in the V8 models. I leave it on whenever I get a 4-banger loaner as the sewing machine noise is nasty at idle. Much more pleasant if the engine turns off, and on those cars it generally stays off until I move again, but in the AMG this feature is largely pointless. Not sure what you are hoping to gain from it, but the potential fuel savings are at best a rounding error 
. Take a more efficient car if you are frequently stuck in city or stop&go traffic.
. Take a more efficient car if you are frequently stuck in city or stop&go traffic.
Last edited by superswiss; Jul 23, 2021 at 06:15 PM.
MBWorld Fanatic!
Joined: Oct 2020
Posts: 1,184
Likes: 891
From: Arizona
Bentley Continental GT; AMG GT
Yes, there are several parameters that go into the decision of when to stop the engine. One of the main parameters is cabin temperature. If the AC is working overtime to keep you comfortable, the engine won't stop as otherwise the cabin temperature would rise quickly. It's a pretty misplaced feature on an AMG frankly. I turn it off first thing after starting the engine. When it's on, it often stops the engine just to restart it again a few seconds later resulting in increased fuel consumption and unnecessary wear. The engine has to be off for about 7 seconds to really save fuel, but with everything that's going on it doesn't seem all that effective in the V8 models. I leave it on whenever I get a 4-banger loaner as the sewing machine noise is nasty at idle. Much more pleasant if the engine turns off, and on those cars it generally stays off until I move again, but in the AMG this feature is largely pointless. Not sure what you are hoping to gain from it, but the potential fuel savings are at best a rounding error . Take a more efficient car if you are frequently stuck in city or stop&go traffic.
. Take a more efficient car if you are frequently stuck in city or stop&go traffic.
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Joined: Sep 2017
Posts: 1,025
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From: Santa Monica Mountains
2025 Lucid Air Grand Touring, 2022 F-150, 1926 Rolls-Royce SSG roadster
The start-stop feature is on there to meet Euro fuel consumption standards. Nothing more, nothing less.
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