2019 Cayenne fails to restart after stop start - Page 1 - Porsche General - PistonHeads UK

Having a pretty crap end to the year, first my fridge died just before Xmas, now the car is playing up. Any help/advice greatly appreciated as it’s out of warranty, so contemplating trying a (UK) specialist first. This evening I came to a junction and it cut out, then wouldn’t restart, no error showing. Eventually after turning the starter a few times it started. Went around the corner and it did it again, this time . This time I’d definitely come to a stop and the stop start seemed to have been engaged. This time it complained about the key battery being low and there was a yellow car symbol with a “!” In the middle. Turning the starter all the internal electronics worked as normal but the engine didn’t crank at all. After around 5 minutes of trying it did it again. On the way home I caught one red light and the same thing happened. This time I got an error, “engine control fault, driving permitted”. Again everything else worked but the engine would not crank at all. After a few minutes it started and I got home. As I stopped on my drive I got a “start/stop” errror. It’s a 2019 base Cayenne (UK), owned from new with 19k on the clock. Im contemplating changing the battery in the hope thats the problem. But otherwise I imagine it will be an expensive investigation at the main dealer where its always been serviced. ​​​​​​​Any help advice greatly appreciated.

Sounds like the battery to me. Have you got a trickle charger or battery conditioner? Might even be worth checking the battery voltage when the car has been sat for a few hours

justin220 said: Sounds like the battery to me. Have you got a trickle charger or battery conditioner? Might even be worth checking the battery voltage when the car has been sat for a few hours Thanks for the advice. No, I lent it to someone and they never gave it back, plus I think the car may have a LiON battery :/ I’ve just remembered I have RAC cover via my travel insurance, will give them a call and hopefully get an initial diagnosis. Given my low mileage the battery would be a prime culprit. But it’s odd the car didn’t complain at all about the battery voltage. Edited by 5to1 on Tuesday 17th December 20:41

Following some advice on Rennlist, I’ve ordered the NocoGenius10, hopefully trickle charging the battery will help.

Checked this morning and I do indeed have a LiON battery (LG Chem) 🤦‍♂️ The battery voltage on the PCM was showing 13v, but that doesn’t reflect what it produces under load. RAC came out and sure enough it started without issue for him. He couldn’t find any error codes (they’re apparently in the process of securing a login to Porsches secure system). He advised trying the trickle charger as it’s often the battery in his experience. Otherwise it has to go to Porsche. Having done some reading a replacement battery is ~£2k. Thanks for that Porsche!

anonymous said: [redacted] I’ve been having a read of others experience and they’ve posted it’s set them back ~£1800 at Porsche. I’ve then had a quick google and saw even the refurb/used ones are up at ~£800-£999 on the likes of eBay. Porsche in their infinite “wisdom” appear to have lumbered these cars with very expensive LiON battery’s. There is the possibility to convert to AGM but no official solution.

We had something similar on ours and it was diagnosed as a problem with the starter motor attached to the stop start system, apparently a known fault and covered under warranty.

Thanks, that’s another possibility. Did yours try to crank the engine at all? Mine is out of warranty as I was planning to change cars, so unless there’s a recall I’m guessing I wouldn’t be covered :/

Ours didn’t crank at all, the electrics worked (with similar engine warning lights to yours) but it wouldn’t do anything at all and had to be put on a flatbed. It might be possible to try and get a gesture of goodwill from Porsche but they’ve not been much help on certain issues, even with a warranty.

Mosdef said: Ours didn’t crank at all, the electrics worked (with similar engine warning lights to yours) but it wouldn’t do anything at all and had to be put on a flatbed. It might be possible to try and get a gesture of goodwill from Porsche but they’ve not been much help on certain issues, even with a warranty. Thanks, sounds very similar in that case. Not sure I’ll get much goodwill despite the low mileage. But I could always take it to an independent.

Mosdef said: We had something similar on ours and it was diagnosed as a problem with the starter motor attached to the stop start system, apparently a known fault and covered under warranty. Looks like you were right. Got a local specialist out with their PIWIS and it’s showing a starter motor fault “locked out electrical or mechanical fault”. Waiting on quote from OPC, will give Porsche GB a try given it’s only done 18k, but not holding my breadth.