Bad software is turning some Mustang Mach-Es into ‘electric bricks’

Photo by Sean O’Kane / The Verge

Charging is a common concern with electric vehicles. But some owners of the brand-new Mustang Mach-E have run into a peculiar problem: their electric SUVs won’t start even when the main battery pack is full.

That’s because, The Verge has learned, there’s a problem with some early Mustang Mach-E SUVs that involves how the much smaller 12-volt battery gets charged. It’s the latest in a growing line of small issues that have come to light during the rollout of Ford’s first long-range electric car.

As is the case in other electric cars, the Mustang Mach-E keeps its 12-volt lead-acid battery topped up by essentially sipping power from the much larger lithium-ion battery pack. Based on owners’ accounts across multiple forum threads, including one who spoke to The Verge, the problem is this stops happening whenever the Mustang Mach-E is plugged in to charge up the larger battery pack.

That is especially an issue for owners in areas with cold weather, as Ford encourages them to leave their Mustang Mach-Es plugged in so the SUVs can use power from the grid to warm up before driving.

The 12-volt battery powers many of the Mustang Mach-E’s systems (since the larger battery pack is high-voltage), and so when it dies, the electric SUV cannot be started. When this happens, owners have reported the FordPass app says the vehicle is in “deep sleep” mode. Some forum members have started referring to it as the “electric brick” problem.

Ford recently filed a technical service bulletin with the National Highway Traffic Safety Administration that confirms the problem has to do with the software on the powertrain control module. Ford wrote that this only affects Mustang Mach-E SUVs built on or before February 3rd, meaning it’s possible that dozens are affected. (Ford would only say that a “small number” of the nearly 7,000 Mustang Mach-Es delivered in the first three months of the year have the issue.)

Right now, those owners cannot get the fix via an over-the-air update. The company said in a statement that they’ll have to bring their Mustang Mach-Es to a dealer:

We are aware that a small number of Mustang Mach-E owners have had their 12V battery reach a low voltage condition. We proactively worked with early owners experiencing this issue to identify the root cause and a fix. In the rare instances where this still occurs, customers can now contact their local EV-certified Ford dealer to have the matter resolved.

Ford did tell The Verge that the problem will be fixable via wireless update “later this year” and that Mustang Mach-Es currently coming off the line should not be affected.

It is possible to jump the 12-volt battery, just as you would jump-start an internal combustion car. But it’s not nearly as straightforward, especially because the battery is located behind the Mustang Mach-E’s front trunk, and the hood’s electronic latch is powered by the low-voltage battery.

To first open the front trunk then, owners have to open a panel in the front bumper that contains two leads, which can be used to jump the front trunk’s electronic hood latch. Then they have to pull back a panel underneath the hood to find the battery — though even at this point, some owners have had trouble accessing the leads on the 12-volt battery and have cut through the vinyl to more easily jump-start the battery.

Ford offers free roadside assistance with the Mustang Mach-E, too, so owners have this as an option if they need to get their electric SUVs towed to a dealer. The roadside assistance is also supposed to include 12-volt battery jump starts, according to the owner manual.


Update April 8th, 5:48PM ET: Clarified in the tenth paragraph that owners have discussed on Mustang Mach-E forums cutting through the trunk panels to more easily access the battery, rather than out of necessity.


Ford learning a lesson that Tesla already learned the hard way which is that the bare minimum battery needed doesn’t quite get the job done. I don’t pretend to know much about it, but you’ve got a lot of electronics that need to run persistently and a lot of crazy stuff coming on line at any given time. So if you stay idle for too long it stresses the battery. My 2006 F150, by contrast, gets driven about once a month but isn’t really doing much electrically in the interim. It also has a much larger battery.

That said I can’t imagine why this needs a factory software update to resolve. Tesla just came out and gave me a new battery.

Naw it was just a software issue. It’s been addressed. Sucks for the owners who’s cars were affected though.

Cost-cutting is going to doom electric cars.

I don’t think this problem has much to do with the car being an EV

Issues are
- Phantom drain on the 12v battery
- 12v battery cannot be easily accessed when it goes flat
both of which could happen on an ICE vehicle just as easily

But in an EV, improperly written software may not charge the 12v when the car is running on those high charge batteries. In ICE cars, the 12v gets charged when the engine is running.

You just mean there’s an easy fix (jump) on ICE cars.
The flip side is you’ll never have to jump your 12v in an EV if the software is written correctly

The same could apply to an ICE car (indeed BMW has all sorts of issues with the car not being aggressive enough at keeping the 12v battery topped up, done for fuel economy reasons IIRC)

12 volt battery stuff seems to be a very common issue with EVs generally.

Every new Ford vehicle released recently has had some noticeable issues, which is why ill be waiting about two years for the Bronco

I’ve had the MachE over a month. Zero issues. I think this affected a small # of cars that came off the line in the first week of production.

Affected owners need a dealer to fix it

It’s not an issue if the vehicle is able to use it’s over-the-air-updates to fix it, the problem is only a problem because these few affected owners now have to suffer a trip to their dealership to fix the issue.

American Automobiles

This issue was addressed a month ago. Small # of cars affected and software update taeks care of it. Old news.

It’s deja vu all over again. VW had the identical problem with the ID.3 in Europe. They don’t have OTAs working yet either so the early owners had to take their in to the dealers to get the software update. This sort of thing is why it’s so important that both of them get OTAs working.

It’s just early adopter woes

Where that tweet from Ford’s CEO about their quality? Lmao, I’m sure the Mach E is a good vehicle but I couldn’t drive something called a Mustang, has 4 dots and pretends to be a CUV

Battery drain issues are definitely not unique to EVs and at least this is something that can be fixed (in the future) via a software update.

I had a 2005 Acura TL 6 spd. Loved that car. But a few years after owning it, I had constant issues with battery drain. The first time I bought a new battery. The second time (happened too quickly after buying the battery), I decided to do some research.

Turns out a shorted out HandsFree module was draining the battery every night. Found countless vides on how to fix it:

Youtube videos

It was so common that there was even a class action lawsuit, but it didn’t go anywhere.

So you can’t access the lead-acid battery because the electronic latch to the front hood is powered by…the lead-acid battery. Genius.

I managed to buy my new Ford! Thanks

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