Auto start/stop not working
03-10-2023, 10:24 AM
#16
Rennlist Member
There's some variables here in play (temp, electronic load such as if you're headlights are on), but that's on the low side. So yeah, probably looking at the battery.
14's are not normal voltage. Call it around ~12.6 as "healthy."
Also, just worth noting since it's cold outside, is that auto start-stop will not function with seat heaters on.
14's are not normal voltage. Call it around ~12.6 as "healthy."
Also, just worth noting since it's cold outside, is that auto start-stop will not function with seat heaters on.
03-10-2023, 11:23 AM
#17
Three Wheelin'
12.6 volts is the normal at rest full charge. Some premium batteries like Optima are higher. 12.0 is 25%. Supposedly minimum 11.9 to start a car. I agree that there are many variables for Start Stop to work, Strongly suspect you have a failing battery. Suspect its the original and five+ years old. Check the date stamp on the post. A new AGM battery charges at 14.8 with the car running and then drops to 13+. CPO supposedly covers the battery, especially if you just picked it up.
03-10-2023, 11:34 AM
#18
RL Community Team
Rennlist Member
Rennlist Member
You all may know this already, but the instrument cluster voltage indicator is not always the same as what is at the battery terminals, due to the use of a DC/DC control unit to manage momentary voltage drops in the system. If you're concerned about the battery health, have it tested!
03-10-2023, 11:47 AM
#19
Addict
Rennlist Member
Rennlist Member
Another symptom of a low battery is that the Active Comfort Entry (assuming you have this option, where the seat automatically slides back on exit and forward to the preset when you enter and close the door) doesn't work.
03-10-2023, 01:13 PM
#20
Rennlist Member
On the same topic, how long will your Cayenne be able to keep the engine off during auto stop/start with a healthy battery? Mine will occasionally turn off at a stop, but most times I am in the same boat as OP. And if mine does turn off, it isn't able to stay off for more than 15 seconds at the absolute best, and I could watch the voltage drop from nearly 15V to around 11.6 when the vehicle turns back on just in that 10-15 second timeline. That's not normal i.e. I likely need a new battery soon right?
My previous F15 X5 and F80 M3 both could stay off for nearly 3 minutes at a time before coming back on so that's somewhat where my expectations lie, but any feedback on how yours works with a confirmed healthy battery is appreciated as well.
My previous F15 X5 and F80 M3 both could stay off for nearly 3 minutes at a time before coming back on so that's somewhat where my expectations lie, but any feedback on how yours works with a confirmed healthy battery is appreciated as well.
03-10-2023, 01:43 PM
#21
New car should be right. Regardless of whether "the stop start shouldn't work so and so" Get the battery tested. If it is weak or bad the dealer owes you a new one. Just done that exact same thing on mine in the UK. Here ( never mind any warranty ) any dealer that sells a car HAS to cover it for 3 months from date of sale. A faulty battery is part of the cover. If a car won't start because of a duff battery it is an ornament, not a car! If your battery tests weak or bad it won't be long before you have an ornament.
03-10-2023, 05:23 PM
#23
@mstrmoo CPO should essentially guarantee a fault-free car, and a car with an non-working start stop system would be a PR issue, no matter the cause.
A weak battery will cause all sorts of weird issues in a german car, as you probably know. I'd call the dealership and ask them to deal with it.
That having been said, half this forum would love to figure out how to defeat start-stop without buying an aftermarket gadget.
A weak battery will cause all sorts of weird issues in a german car, as you probably know. I'd call the dealership and ask them to deal with it.
That having been said, half this forum would love to figure out how to defeat start-stop without buying an aftermarket gadget.
03-10-2023, 05:24 PM
#24
03-10-2023, 05:33 PM
#26
I just picked up at CPO 2018 Cayenne base.
On the drive home I noticed start/stop doesn't work, and a light comes on in the dash indicating start/stop fault. I assumed it's a weak battery.
I messaged the sales rep about it. He said it's because the outside temperature, or engine/interior aren't warm enough and it will work when temperatures improve. It was 38 degrees today. Seems odd, only because I'm coming from a C-class that never had an issue at these temps... Am I missing something? Is this a Porsche thing?
If it's the battery, I understand it's a wear item and not covered under CPO, but I would assume it would be looked at and corrected during the CPO process.
Anyone have any insight?
On the drive home I noticed start/stop doesn't work, and a light comes on in the dash indicating start/stop fault. I assumed it's a weak battery.
I messaged the sales rep about it. He said it's because the outside temperature, or engine/interior aren't warm enough and it will work when temperatures improve. It was 38 degrees today. Seems odd, only because I'm coming from a C-class that never had an issue at these temps... Am I missing something? Is this a Porsche thing?
If it's the battery, I understand it's a wear item and not covered under CPO, but I would assume it would be looked at and corrected during the CPO process.
Anyone have any insight?
03-10-2023, 05:33 PM
#27
Track Day
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Car sat overnight. Turned on electronics in the morning. Voltage on the dash showed 12.1, then went down to 12.0 and 11.9 within a few seconds.
03-23-2023, 12:49 AM
#30
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Did not get it tested yet. Does this seem like a long cold crank? Sat overnight. 2018 base.
Also, driver seat does not fully return to memory position most of the time on warm start, but always returns on cold start.
Also, driver seat does not fully return to memory position most of the time on warm start, but always returns on cold start.
Last edited by mstrmoo; 03-23-2023 at 12:52 AM.