Toyota has a knack for heartbreak in the final moments of Le Mans, and even though the team won overall this year with its No. 8 car, the No. 7 car that had been in the lead found a way to have a disaster. Multiple tire changes as the result of a supposedly faulty tire sensor saw that leading car take a sorrowful second. Now, Toyota is letting us know exactly what went wrong.

What exactly did the team screw up? The tire pressure sensors were wired up incorrectly to the antennae that communicate with the pit wall, reports.

So, it wasn’t a problem with the sensor itself, like Toyota initially thought. The team had just wired up the car wrong. The antenna that was supposed to be picking up a signal from the left front tire was actually picking up signals from the left rear, and vice versa. The sensors were working perfectly fine; they were just transmitting to the wrong place.

It feels like one of those mistakes where hindsight is especially 20/20. Of course, it’s unlikely that the problem would be detected earlier in the weekend if everything was performing perfectly. But at the same time, it’s a screw-up that a team like Toyota shouldn’t have made in the first place. I’m no race team, but I feel like making sure your equipment is transmitting to the right place is pretty important.

And then, there was the team’s decision to change only one tire when the sensors indicated there was a low pressure. It makes sense in some ways—it’s faster which would enable the No. 7 to get back in action, and there’s no reason to imagine the whole sensor system would be slightly disastrous. But on the other hand, if you had a sudden puncture, I’d feel way more comfortable changing all the tires, just to make sure it wasn’t the result of some debris. This is Le Mans, after all—it’s not necessarily speed that counts, but reliability.

Alas. There’s nothing Toyota can do now other than (hopefully) to learn from the problem for next year. But damn, what a downer.