PSA: Don't let your tank run dry

This is a known issue. We learned very long ago that, at least in Gen3, there has a lockout after some number of attempts to restart without sufficient fuel, or whatever else prevents the ICE from running. This seems to be a protection of the hybrid battery, to prevent drivers from endlessly trying to restart until the battery is drained to the point of not being able to crank the ICE, thus requiring a special hybrid battery charger to bring it back up. Back when Gen3 was still fairly new, there were very few of these chargers in all of North America, needing to be shipped from dealer to dealer as needed.

Over-drained traction batteries were a very real problem in Gen1 (and maybe Gen2 also?), as drivers continued driving and/or cranking without gasoline trying to reach too-far gas stations, and caused real battery damage. This was much worse than simply draining an easily-jumped-started 12V battery.

This lockout effectively forced drivers to quit futilely wasting battery charge and go do something else to fix the real underlying problem. Even with a tow and shop service, this is still less expensive and time consuming than what older generation drivers experienced.

The first member here to intentionally run his Gen3 2010 out of fuel, for engineering tests and curiosity and to report back to us the signs and symptoms and behavior, promptly re-fueled from his spare fuel can and it started right up with no problem. He didn't try restarting before fuel was added.

Not long thereafter, another member accidentally ran out, then tried repeated restarts without adding fuel, got locked out from further restart attempts, and needed a tow to a dealership where it was reset. A while after that, others discovered that a dealership reset wasn't really needed, as disconnecting the 12V battery long enough to clear volatile computer memory, did the same thing.

So this car behavior isn't really eff'ed up. It is to prevent you and other from eff'ing up their traction batteries.

Unfortunately, your Prius Owner's Manual doesn't describe all of this.

 

How many times did you try to restart, before adding a couple gallons of fuel?

As a long-time member posted in June 2009, you can add gas and drive to a gas station -- if you haven't already triggered the lockout point. This was found just a couple months after Gen3 was released in the U.S., by a member who intentionally ran his (by then) 2 Prii out of fuel more than 50 times for a wide variety of interesting tests to be reported here. And he was never locked out. The lockout, and then a solution without a shop visit, were found a bit later by others who didn't add fuel before multiple restart tries.

While not ideal, this was a very clear improvement over prior designs. The car could be disabled by any of numerous other problems too, this lockout protects the battery across a wide class of problems. It just doesn't dive deeper to separate this from the others.

But unlike today's mobile phones, these cars do not receive regular software updates for bug fixes and feature updates. The basic software in your car is now over 15 years old, we have since been spoiled by newer and better things that get software updates every couple weeks or months.

These cars are now old tech. My Gen3 was far far ahead of the 20th Century car it replaced. It just couldn't benefit from 20/20 hindsight fixes that my mobile phone can today.