So my new RRS HST P400 is about a month old and I’ve realised that the auto stop/start function has stopped working.

I was definitely working on day 1, but I do recall that i tried to turn the function off. Seems I succeeded... permanently.

As far as i can tell, this function isn’t one that we are supposed to be able to turn off permanently, but in my car, when idling at a standstill, it puts up the “auto stop/start inhibited “ sign, which is the letter A ,white in colour with a line through it.. Its been doing this for at least 3 weeks, possibly since i tried to turn it off originally.

Google tells me it could be a battery issue, but is that likely in a brand new vehicle? Any help appreciated, have rung Stealer as well. current: RRS HST P400 engine ( 2021) Hakuba silver

Battery problems are common in older cars where they have two batteries. In my D4 there was a bad batch, so it is possible. Should be easy for the dealer to check........famous last words  Joined the X5 45e club
1994 Defender 90 300 tdi

Charge your 12V battery overnight and see what happens the next day.

Concur with KOT - stick it in a trickle charger and should be sorted MY16, 3.0D HSE Dynamic, Barola Black, TV, Rear Entertainment, Opening Pan Roof, Meridian

Thanks all.
Not sure how a brand new car can have a battery that is too low in charge. This problem occurred within 2 days of me getting the car. current: RRS HST P400 engine ( 2021) Hakuba silver

Charge the battery (it may have been stnading for a while (as in on the shelf) and all the checks etc... could just be low.

The ASS only works under certain conditions so if you there is high demand on the systems it might kick in straight away!

ASS kicks in as long as these are true but also that you dont have heated steering wheel or seats or high AC etc...

External Temp is less than approx 0 degrees C
External Temp is more than approx 40 degrees C
The engine has not reached temperature
The driver’s seatbelt is not fastened
Demand from the AC requires the engine to be running i.e. defrost
Battery is low (lots of short trips can result in the battery never getting a chance to reach a good charge)
Bonnet/hood is open.

Couple in the battery with lots of little trips about and it could just be low! If a jobs worth doing, get a someone who knows what they are doing to do it!

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RR P38 HSE V8
RRS Supercharged Santorini
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It does not take long for the battery to be low enough for the stop/start not to work. Short journeys, few things on, including wipers & lights. If locked the alarm is taking some power. My car is only used once or twice a week, but always on a Ctek. No problem with stop start.
This shows how quickly a battery looses its efficiency. Check yours.

Same I added a couple of the CTEK quick connectors so I could easily plug in. Have them both in tail (mine is an older car so has 2 batteries from 2016 on I think they used capacitors so a new car will probably us that unless it hybrin then its not an issue.

CTEK MX5.0 or higher great little tools and they can recon AGM batteries now.
These cars chew batteries as they have so many systems running even when its off, like Lind said lights, fridge, heaters, maybe heated seats or steering wheel and AC will all use some power factor in the load used to start the thing too. it wouldnt take long for the battery to drop with lots of little stop start journeys around town as the alternator probably doesnt have enough time to run to put back in what has been taken out each time it starts so it might only be putting back in 50% of what has been used so unless it goes for a good long run or gets charged the battery might be in deficit all the time, a long run might just push it into having enough charge for ASS to kick in but then a few more little trips and its out of charger range

I put a 2 new batts in mine and ASS works fine but with a few little stop start jounreys when its kicked in and im sat at the lights it will sometime fire the engine up (Im guessing this is becuase the car thinks there is too much demand on the battery or its charge has dropped enough that it should have the engine running) maybe its the cold weather but thats on a brand new battery.

It the short trips that do it (not that good for the DPF either but hey ho! It a Range Rover thing, not sure if other cars similar have the same battery drains.

L320 we the same even when off there is still the alarm and keyless stuff that is all still using power, granted not much but over time. If a jobs worth doing, get a someone who knows what they are doing to do it!

RRS Autobiography Indus
RR P38 HSE V8
RRS Supercharged Santorini
AMG CLK Rear Tyre Shredder

As pjbracer1, I also have Ctek quick connect in boot & another in the front which appears from the slot just above number plate so I do not have to open the bonnet & when disconnected it hides inside the slot area. Same here, sitting at lights for a while it switches off then sometimes fires up the engine, so it shows how sensitive it is. Also noticed if you only have your foot on the brake very slightly it will not switch off, but a bit more pressure & it will. I do this at certain junctions where you have to "force" yourself out into the traffic & do not want it switching off.

As part of my routine, my finger goes to the 'eco' button turning the stop/start off, straight after the engine start button.
It is very frustrating that it does not remember its previous setting or that you cannot set it to default 'off'. RRS HSE Dynamic SDV6 2014

Nemo mortalium omnibus horus sapit

If you got a GAP Tool I think you can disable it. I dont mind using it in and around town in the summer when windows are open etc... and its seems a bit of a waste just burning fuel in a queue (im not a greeny, just think we waste alot of resources)

The one thing that is annoying though is reversing as soon as you pull up it will cut out and then has to restart when you try to reverse. Ive been aught out at the marina trying to park when its busy and it looks like you have stalled!

I do find myself turning it off alot of the time as im sure it miust have and effect on the battery over time so the Ctek is a worth investment. If a jobs worth doing, get a someone who knows what they are doing to do it!

RRS Autobiography Indus
RR P38 HSE V8
RRS Supercharged Santorini
AMG CLK Rear Tyre Shredder