Auto Start/Stop strange behaviour

IanS100 · 02-18-2012, 07:36 AM

I left an appointment yesterday & after driving a couple of miles pulled in to check an address and as usual the engine stopped automatically. I left the engine off while I was messing about with paperwork etc and then, after about 5 minutes, the engine started up again

. I hadn't touched anything and can only guess it was because the engine had cooled (Auto Stop/Start doesn't function when the engine is cold) As this has happened a couple of times before I'm guessing it's normal behaviour but it's still a bit unnerving, has anyone else experienced this?

AlanQS · 02-18-2012, 08:05 AM

Battery condition is the most likely explanation. I do a lot of short journeys and the stop/start wasn't working even with the temperature high enough but after a 10 mile trip into town and straight back again, it was working just fine.

If the battery has been a bit on the low side, I have found that the car will re-start after about half a minute - especially so if it's at night and heating, headlights etc., are on.

But if you do 10 miles plus (in one trip), on a daily basis, you shouldn't expect any problems at all.

dobsy · 02-18-2012, 08:12 AM

Mine re starts itself sometimes after a minute or so at the lights when tootling round-I would'nt worry, as said it's the battery sorting itself out.

IanS100 · 02-18-2012, 08:33 AM

I'd done a 20 miles journey, stopped for 25 minutes and then did another 2 miles before stopping the second time - it was a few minutes after the 2nd stop that it did the Auto Start so I wouldn't have thought it would be battery but you never know - it's still very disconcerting

doughboy · 02-18-2012, 09:13 AM

It shouldn't be too disconcerting as it will only do it when you are in neutral, but it did surprise me the first time my van did it.

All sorts of thing could cause this.

If the climate can't maintain the set temp it will restart, or as said if the battery drops a little.

Also if the brake vacuum drops (as it may do after a few minutes) it will restart too.

Try pressing the brake pedal a few times when its stopped and it will immediately re-start as the vacuum is used up.

02-18-2012, 07:36 AM	#1
IanS100 Major General 135 Rep 5,050 Posts Drives: 520d F10 LCI M Sport Join Date: Nov 2011 Location: Southport UK iTrader: (0)	Auto Start/Stop strange behaviour I left an appointment yesterday & after driving a couple of miles pulled in to check an address and as usual the engine stopped automatically. I left the engine off while I was messing about with paperwork etc and then, after about 5 minutes, the engine started up again . I hadn't touched anything and can only guess it was because the engine had cooled (Auto Stop/Start doesn't function when the engine is cold) As this has happened a couple of times before I'm guessing it's normal behaviour but it's still a bit unnerving, has anyone else experienced this?
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02-18-2012, 08:05 AM	#2
AlanQS Colonel 248 Rep 2,815 Posts Drives: Jaguar XE P250 HSE Join Date: Jan 2008 Location: Glasgow iTrader: (0) Garage List 2016 430i m-sport G ... [0.00]	Battery condition is the most likely explanation. I do a lot of short journeys and the stop/start wasn't working even with the temperature high enough but after a 10 mile trip into town and straight back again, it was working just fine. If the battery has been a bit on the low side, I have found that the car will re-start after about half a minute - especially so if it's at night and heating, headlights etc., are on. But if you do 10 miles plus (in one trip), on a daily basis, you shouldn't expect any problems at all.
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02-18-2012, 08:12 AM	#3
dobsy Private First Class 6 Rep 133 Posts Drives: E92 320d Join Date: Apr 2010 Location: Wirral iTrader: (0)	Mine re starts itself sometimes after a minute or so at the lights when tootling round-I would'nt worry, as said it's the battery sorting itself out.
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02-18-2012, 08:33 AM	#4
IanS100 Major General 135 Rep 5,050 Posts Drives: 520d F10 LCI M Sport Join Date: Nov 2011 Location: Southport UK iTrader: (0)	I'd done a 20 miles journey, stopped for 25 minutes and then did another 2 miles before stopping the second time - it was a few minutes after the 2nd stop that it did the Auto Start so I wouldn't have thought it would be battery but you never know - it's still very disconcerting
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02-18-2012, 09:13 AM	#5
doughboy Major General 1578 Rep 8,971 Posts Drives: 2018 M2 Comp 6MT Join Date: Jan 2009 Location: UK iTrader: (2)	It shouldn't be too disconcerting as it will only do it when you are in neutral, but it did surprise me the first time my van did it. All sorts of thing could cause this. If the climate can't maintain the set temp it will restart, or as said if the battery drops a little. Also if the brake vacuum drops (as it may do after a few minutes) it will restart too. Try pressing the brake pedal a few times when its stopped and it will immediately re-start as the vacuum is used up.
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