An unlikely story

Or: sometimes the obvious answer isn’t the answer at all.

We have a relatively recent vehicle which, being recent, suffers from having a significant amount of software in its vitals. I just hope that the safety-critical components are less buggy than the user-facing ones¹.

It has two electronic keys. A few days ago one of them started to be difficult to use: it would sometimes fail to do anything, at other times it would unlock the vehicle which would then refuse to start, or emit panicked messages after it had started saying there was no key.

So, obviously, this was the battery dying. I ordered two batteries since the other key was probably also on its way out.

Before the new batteries arrived the other key started having similar symptoms. Which was an odd coincidence: it seemed implausible that two batteries with a life of years would choose the same week to run down. But the second key was less sickly than the first, so perhaps it was reasonable.

Before the new batteries arrived I found a stash of unused ones I had bought some time ago. So, of course, I replaced the battery in the first key. Which didn’t fix it: now it could unlock the vehicle but not start it or lock it. So, perhaps that key was failing?

I replaced the battery in the other key. Which did not fix it.

So, OK, this leaves one obvious candidate: the vehicle. Aside from the general crapness of its software, it’s also had a history of electronics-related failures so, obviously, this was just one more expensive electronic tantrum. There was nothing wrong with the keys and never had been: the vehicle was just losing its mind, again. That’s why both keys had ‘failed’ in the same week: they hadn’t. And the vehicle was going to need yet more expensive fixing which probably would amount to a firmware update.

And then the new batteries arrived. And because anything would be cheaper than getting the vehicle fixed I tried them. And they worked, in both keys. What had actually happened is that, yes, both batteries had died within a day or so of each other after half a decade, and the unused (in their blister packs) ones I had used to replace them were no good or, perhaps, too old².

Sometimes the obvious answer isn’t the answer at all.