Start stop issue

[alillistone]

Hello all,

I brought a new polo gti in 2019. Since then, I get this random collection of symptoms that all happen at one;
- start-stop system stops working; vehicle status says the engine must be running when it’s clearly sitting idle doing 900rpm

-full consumption increases; my usual trip to work nets me 40mpg but with these symptoms it goes down to 20 mpg

- engine noise is much louder even though my driving mode is in normal preset not sport.

There are no vehicle entries in the system that indicate a fault with the car. I’ve has been serviced twice since I brought it new.

Would appreciate any recommendations of what to do and what to look for? Happy to provide clarity if needed.

[SRGTD]

Sounds like it’s going through a GPF regeneration. Classic symptoms on the GTi / GTi+ are some or all of the following; increased fuel consumption, louder exhaust note, a ‘hot’ smell, slight hesitancy or lumpiness of the engine. I’m assuming the status message regarding the engine running is actually trying to tell you to keep the engine running until the regen has been completed - it could be worded better though. I’m not surprised that stop start doesn’t work during a regen, especially if the car’s status is indicating that you should keep the engine running.

You’ll get more regenerations if your driving is mainly short journeys. My car did one the other day - I think it was the first in just under a year of ownership. I got the louder exhaust note and a ‘hot’ smell but no other symptoms. Don’t know if there was a message under the car’s status re. keeping the engine running or if stop start was inactive as I always have stop start turned off. The fuel consumption didn’t seem to be affected on that journey which is a journey I undertake regularly so I know what mpg I usually get. I did go a couple of extra miles until the exhaust note returned back to normal which to me was an indication the regen was complete.

There’s a fairly lengthy discussion thread at the link below on GPF regenerations.

https://www.uk-polos.net/viewtopic.php?f=71&t=73177

[alillistone]

Sounds like it’s going through a GPF regeneration. Classic symptoms on the GTi / GTi+ are some or all of the following; increased fuel consumption, louder exhaust note, a ‘hot’ smell, slight hesitancy or lumpiness of the engine. I’m assuming the status message regarding the engine running is actually trying to tell you to keep the engine running until the regen has been completed - it could be worded better though. I’m not surprised that stop start doesn’t work during a regen, especially if the car’s status is indicating that you should keep the engine running.

You’ll get more regenerations if your driving is mainly short journeys. My car did one the other day - I think it was the first in just under a year of ownership. I got the louder exhaust note and a ‘hot’ smell but no other symptoms. Don’t know if there was a message under the car’s status re. keeping the engine running or if stop start was inactive as I always have stop start turned off. The fuel consumption didn’t seem to be affected on that journey which is a journey I undertake regularly so I know what mpg I usually get. I did go a couple of extra miles until the exhaust note returned back to normal which to me was an indication the regen was complete.

There’s a fairly lengthy discussion thread at the link below on GPF regenerations.

https://www.uk-polos.net/viewtopic.php?f=71&t=73177

This is the ticket! Thanks a lot for linking that thread. All the symptoms line up. My recent journeys have been quite short < 20 miles so might explain why it hasn’t yet completed its cycle by now.

[Andy Beats]

This is the ticket! Thanks a lot for linking that thread. All the symptoms line up. My recent journeys have been quite short < 20 miles so might explain why it hasn’t yet completed its cycle by now.

Drive faster
Shame if you can't, but my commute is only 4 miles each way and I didn't have any GPF regens in my GTi or previous TSi.
I appear to have been fortunate my journey has one bit that allows me to absolutely nail the cars right through the gears.
Who knew petrols would give as much filter related nonsense as diesels....

[Jurki]

If youre still facing the issue then check your battery. You would be surprised to know how many issues a bad battery can bring.

[steeve]

Take it for a good run, a trip up a motorway is ideal.

[RUM4MO]

I've found that if you have an EFB type of battery, then running a "recon" charging program on it can revive it, I do that in early Spring time on my wife's 2015 VW Polo, and until this year, that has worked, this year nothing has changed after using that charging program, but other than the health dropping from 640A CCA too 450 CCA, there is no other clues as to how that battery is surviving, auto stop/start, when allowed will switch off the engine.

Though hopefully with a GTI Polo, I'd hope that you would have an AGM type of battery, so using "recon" is not useful or advisable, so a monthly or every other month overnight charge from a smart charger should get it back working okay.

[2fast4ya]

Hmmm interesting!?
I noticed about two weeks ago my stop start wernt active , infact i think its been a lot longer since ive paid attention to it , i thought i had turned it off in the multimedia settings somehow, ive never heard of this regen thingy but the car does sound a bit louder which i noticed before i replaced the fuel filter at the weekend, if mines doing a regen what do i need to do ?

[SRGTD]

Hmmm interesting!?
I noticed about two weeks ago my stop start wernt active , infact i think its been a lot longer since ive paid attention to it , i thought i had turned it off in the multimedia settings somehow, ive never heard of this regen thingy but the car does sound a bit louder which i noticed before i replaced the fuel filter at the weekend, if mines doing a regen what do i need to do ?

If your car is as per your forum signature - a 1.8 GTI - then it’ll be the previous generation 6c Polo. The 6c Polo didn’t have a GPF so your car won’t be performing a GPF regeneration.

Certain criteria needs to be met for stop start to work. Also, if your car’s battery is getting towards the end of its life, then that could be the reason for stop start not working.