Our Tesla Cybertruck's Steering is Fixed — Here's What Happened

• The Cybertruck we bought failed both times we brought it to our test track.
• It went into limp mode after mild use on our handling circuit.
• We took it to a Tesla service center for repair. Here's what they told us.

In August, we reported that the Tesla Cybertruck we bought suffered its second steering problem in a month, requiring another lengthy reboot before it was ready to drive again. After polling the team and determining that a solid majority a) planned on driving at speeds higher than 4 mph and B) generally preferred that the steering system work, we made an appointment with our local Tesla service center so they could solve the problem. The diagnosis, to put it mildly, left us baffled.

To recap: We bought a Tesla Cybertruck Foundation Series in June, and brought it to our test track in July to put it through our standard instrumented testing process. You can read all about what happened here, but to make a ridiculous story short, the truck disabled rear-axle steering, stopped blowing cold air and capped the maximum speed at the pace of a brisk walk. After leaving the car for half an hour, we restarted the truck and everything was back to normal. We experienced the same issue in August, and it took 50 minutes for the Tesla to jolt itself out of haze.

Senior editor Brian Wong handled the service visit. Here's what happened next, in his own words.

"I picked up the truck on Wednesday afternoon and spoke to Jose, one of the technicians who handled our case.

"Our truck was shipped with some coolant, just not enough of it. I asked if they inspect the coolant level as part of the predelivery inspection; they said that they do not as it is supposed to come from the factory with enough coolant.

"I asked why we didn't see any coolant errors; he confirmed that if the coolant is low you should see a coolant error. But the reason we did not is there was air pressure in the system, so the truck thought that the coolant reservoir was full ... even though it was mostly full of air. This would jibe with how the coolant system is filled, which is with a vacuum tool, and implies that the coolant system uses some sort of pressure sensor to detect leaks/how full it is.

"Due to the closed-system nature of this, we are unable to add coolant ourselves. It will have to return to Tesla each time. The mix they use is standard, a mix of antifreeze and water; he didn't know the exact mix.

"He said that was the reason we saw that other litany of errors and not a coolant error. Basically, all of the systems that required cooling started to get hot and the vehicle, thinking it was full of coolant, went into redundancies and shut itself down to protect everything (hence limp mode). So the alerts and warnings about the 48-volt battery, electric motors, rear-wheel steering, battery, etc., that we saw were tied to that.

"Our coolant has been topped off, the techs flushed the system fully (because they have to in order to refill it), filled it, checked for leaks, flushed it again, and refilled it. He said we should be good for 'a few years' at least.

"There is also no way for us to check the coolant level ourselves; we're basically in a 'wait until it dies again' situation, or you get the error from the truck.

"This also leads into a wider conversation about maintenance on EVs, be it coolant, brake fluid, etc."

So there you have it — there wasn't enough coolant in the truck to keep the necessary systems cool, and because the Cybertruck didn't realize there wasn't enough coolant, it thought something major was wrong and cut power to save itself. An underhood fluid level check is part of our pre-test procedures, and we would have caught this ourselves if the reservoir was actually accessible, but as we learned in our visit to the Tesla service center, that simply wasn't possible in the case of our Cybertruck.