Haunted car since FW update on 25/6/2026

[SteveUK]

Just an update...
After a few weeks of normal driving, the demonic possession moved to the drive train, with the car continually insisting I needed to run the petrol engine for an extended period. I know this is a thing as I do a lot of my journeys on EV only. EXCEPT it starts the petrol engine on its own (I'm not pushing to accelerator enough to even start it) and after running for a few seconds, it then switches off petrol engine and goes back to electric... and then started it again, then stopped it again... Loop until insanity.
It makes doing anything on the dash display impossible as the "Engine needs to run" message continually interrupts whatever you were trying to do!

Dealer was hopeless, said it was a fault with a sensor in the HV battery and that they couldn't do batteries and I needed to go to a battery centre, "Oh, and that diagnosis will be £130 please sir". Nearest battery centre is over an hour away in a different county.

I put up with this for a few weeks, and then started experimenting. I ran the battery to 0%, and then just drove it as a petrol with start/stop. At least that was normal, no nag message. Then one day I wondered "what if", and put 30% charge into it, and it drove perfectly normally on EV. Next day I gave it a full charge, and it was fine. It's on charge again right now. This screams software bug at me (I am a programmer by profession).

Of course dealer won't update the software "sorry sir, we only do that if SEAT tell us to". When pushed he then said it would take 4 or 5 hours (hinting at the labour cost of plugging a cable into the car and leaving it).

I also got "told off" for changing my own 12v battery (it was an attempt to banish the demons). What next, need dealers permission to top up the washer bottle?!

My next car is going to have carburettors and a speedo driven by an f'ing twisty cable!

 

[Momochi]

Just an update...
After a few weeks of normal driving, the demonic possession moved to the drive train, with the car continually insisting I needed to run the petrol engine for an extended period. I know this is a thing as I do a lot of my journeys on EV only. EXCEPT it starts the petrol engine on its own (I'm not pushing to accelerator enough to even start it) and after running for a few seconds, it then switches off petrol engine and goes back to electric... and then started it again, then stopped it again... Loop until insanity.
It makes doing anything on the dash display impossible as the "Engine needs to run" message continually interrupts whatever you were trying to do!

Dealer was hopeless, said it was a fault with a sensor in the HV battery and that they couldn't do batteries and I needed to go to a battery centre, "Oh, and that diagnosis will be £130 please sir". Nearest battery centre is over an hour away in a different county.

I put up with this for a few weeks, and then started experimenting. I ran the battery to 0%, and then just drove it as a petrol with start/stop. At least that was normal, no nag message. Then one day I wondered "what if", and put 30% charge into it, and it drove perfectly normally on EV. Next day I gave it a full charge, and it was fine. It's on charge again right now. This screams software bug at me (I am a programmer by profession).

Of course dealer won't update the software "sorry sir, we only do that if SEAT tell us to". When pushed he then said it would take 4 or 5 hours (hinting at the labour cost of plugging a cable into the car and leaving it).

I also got "told off" for changing my own 12v battery (it was an attempt to banish the demons). What next, need dealers permission to top up the washer bottle?!

My next car is going to have carburettors and a speedo driven by an f'ing twisty cable!

Have you tried again after 7:13pm today, after the solar eclipse?? I shut myself in the gym from 6pm to 8pm just to avoid any sunlight (or the lack of it). This may, however, be an omen your car desperately needed, as some con men might have already told you....

Be serious.... Have you tried checking with any independent VAG specialist? Or even hybrid specialists (e.g. Toyota experts)?

 

[SteveUK]

Have you tried again after 7:13pm today, after the solar eclipse?? I shut myself in the gym from 6pm to 8pm just to avoid any sunlight (or the lack of it). This may, however, be an omen your car desperately needed, as some con men might have already told you....

Be serious.... Have you tried checking with any independent VAG specialist? Or even hybrid specialists (e.g. Toyota experts)?

I don't know if they can do software updates (which I suspect is what it needs). My nearest VAG battery specialist is a VW dealer, and they basically weren't interested, even though we all know the car is 99% VW Golf.

For your amusement, this is what it was doing, which the non battery specialist Seat dealer said was a sensor fault in the HV battery and said they couldn't do it.

https://drive.google.com/file/d/1RqsX1GZJrUQbSz9kDiO3oXauKPyNiN_x/view?usp=drive_link

It would even do this under braking, and whilst rolling down a hill with the gearbox in neutral!

I "fixed" it by draining the HV battery completely, driving purely on dinosaur juice for a couple of days with my 1% battery (I don't think it ever says 0%), and then when I put a little charge into it on the 3rd day, it was behaving normally. It's had two full charges since then, and just driven in EV mode just as it should.

In normal use I never drain the battery. I have free charging at work, so I fully charge it there, and it gets me to and from work in EV mode. So to me that smells like something to do with the HV battery monitoring has gone out of calibration, lost track of the cell voltage range, and got confused. Running it "flat" to a "empty" level of charge has got everything to line up again.