New XC40 sudden power loss - safety issue

Faults and Technical chat for the Volvo XC40
Felindre
Posts: 902
Joined: Wed Dec 23, 2020 2:19 pm
Location: South Wales, UK

Post by Felindre »

At 5 weeks old you can reject it.
B4 AWD Inscription , Fusion Red, Blond interior. Drivers Assist, Climate, Tinted rear windows and Towing pack.
Ordered 14 Dec 20, delivered 10 March 21

Den48
Posts: 259
Joined: Sun Dec 20, 2020 10:13 pm

Post by Den48 »

Hi
Are you sure about rejecting the car after 5 weeks? I understand that you can reject a car within 30 days , after this and for up to 6 months you can reject a car but you have to prove to the dealer that a fault (s) existed when the car was purchased/ taken delivery of the vehicle.
T4 recharge, plus spec, 23my
berryberry
Posts: 25
Joined: Mon Dec 30, 2024 7:04 pm

Post by berryberry »

Thanks for your input. You are certainly right about the 'don't trust it' advice. While we are having ongoing discussions with the dealer and Volvo UK we thought it prudent to see what others think and we thought this forum was the right place for alternative viewpoints.

We came on to this forum as we noted that others do share problems and we feel that when you are taking on the might of a large organisation it's quite important to gain the backing of others when down in the trenches - thanks for your support.
berryberry
Posts: 25
Joined: Mon Dec 30, 2024 7:04 pm

Post by berryberry »

Many thanks for your clear advice. For info - we rejected the car within the first 30 days, but we are experiencing great difficulty in getting them to accept that we simply do not want it back .
eugen61
Posts: 1504
Joined: Sun May 10, 2020 7:33 am

Post by eugen61 »

So you already rejected the car before the power loss incident? You said the incident happened 5 weeks after purchasing the car.
2020 T4 FWD Momentum Pro Sensus OS
berryberry
Posts: 25
Joined: Mon Dec 30, 2024 7:04 pm

Post by berryberry »

Sincere apologies - hope that slip does not damage our credibility - we will put it down to reams of correspondence with Volvo - we got the car on 20 November, and it was registered to us on 24 November, the incident occurred on 17 December and we contacted Volvo to advise them of our dissatisfaction on 18 December, and then formally rejected the car on 20 December - all within the 30 days.

Apologies for the confusion.
eugen61
Posts: 1504
Joined: Sun May 10, 2020 7:33 am

Post by eugen61 »

No need to apologize, the important thing is that you’re within the 30-day window. Hopefully everything gets sorted to your satisfaction.
2020 T4 FWD Momentum Pro Sensus OS
neilgorin
Posts: 24
Joined: Mon Dec 11, 2023 2:15 am

Post by neilgorin »

berryberry wrote: Wed Jan 01, 2025 3:00 pm
Hi Neil
The situation that night was that we broke and slowed down to stop at the junction, and the stop/start engaged. We then when it was safe to do so, accelerated, and all was well and the car moved forward 10ft, it then died! Complete loss of all power, lights, the lot. With hazard lights deployed and with seconds to get out of the car, we pressed the starter,the car started and we drove off. The key here is that the stop / start appeared to be working fine as we broke at the junction and then accelerated, it was the involuntary stop that gave us serious safety concerns.
Sounds more like a loose battery lead than anything really.

NB your car doesn't have stop/start as such, it's a mild hybrid - the engine can and will shut down at any speed as well as at rest, but everything else works normally when that happens as unlike a standard stop/start system, your lights, brake servo, power steering and so on are powered by the 48v battery in the spare wheel well in the boot which holds more than enough charge the for car to travel at speed for several miles (downhill on a motorway for example) with the engine off and the gearbox in neutral.

For the car to die totally, it's a major electrical issue OR a loose 12v battery lead, either way it's something the dealer should be looking into and not (like many do) fobbing you off with "we can't replicate the fault, customer to monitor".
berryberry
Posts: 25
Joined: Mon Dec 30, 2024 7:04 pm

Post by berryberry »

Wow

That's an entirely different angle that has not really come up at all but very much appreciated just the same.

Not technically gifted enough to have appreciated how a car can keep moving despite the engine shutting down, even at speed. Of course, in our scenario our car came to an immediate cessation of all power so quite surprised that given your theories, the garage, despite our request that they check all things mechanical and computerised, did not even mention either of your possible reasons.

Disappointing to hear that 'many' dealerships do resort to the fob-off approach.

Thanks for the alternative theories.
berryberry
Posts: 25
Joined: Mon Dec 30, 2024 7:04 pm

Post by berryberry »

Hi Neil

This theory of yours is gaining some considerable traction in our minds, as we researched further and got an answer to suggest that when power transfers from the 12v to the 48v battery, when we would have been nearing the junction for example, it can be that the 48v battery is responsible for providing the initial inertia to take off again, which it did, but then potentially spectacularly failed to transfer back to the 12v operation to proceed further as normal, hence the collapse.

This all seems quite plausible but we may (learning as we go here) be way off the mark. It does appear though that this appears to have happened to others in the past.

Any further thoughts welcomed.
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