HELP!!! Gas engine shut off on highway, plenty of fuel...

Could be any number of things. When is the last time the throttle body was cleaned? How many miles on her now? The mechanic should be able to give you a better idea that what we could based on the information you have shared so far.

Ron (dorunron)

 

Was the engine air cleaner cover opened for any reason recently? The reason I ask is that debris collecting around the edge of the air cleaner cover can fall into the clean side of the air cleaner housing, and eventually make its way into the Mass Air Flow sensor. Any debris in the MAF sensor will disrupt the airflow through the sensor and prevent the Engine Control Module from delivering the correct amount of fuel. A stall from this may not even set a trouble code.

Also note that repeated unsuccessful starting attempts can discharge the Hybrid Battery to a point that the engine cannot be started. I believe the minimum is about 20% state of charge.

 

Oil was low but "some in there" is not good. Your Prius is probably eating engine oil as most do at higher miles (never stated miles) and your never checking the oil. Guaranteed method to lunch the motor on a Prius. It's probably the throttle body was never cleaned and is hopelessly corroded and requiring replacement.

Its good you have a mechanic but its also really important that you know what DTC codes were thrown. All codes including there subsequent 3 digit suffix:
XXXX-XXX

If your mechanic is unable to pull these codes as he lacks the proper OBDII Scanner he may not really be qualified to work on this car as thats the first thing you need to know before you lift the hood. Ask him. You can waste alot of money (yours) chasing a Prius issue unless you know the codes. It sometimes becomes a guessing game of parts replacement on your dime.

If you knew the codes we can almost certainly tell you pretty close what the actual issue is. Sometimes better than your mechanic as we all have alot of experience with this platform.

In the meantime good luck but hopefully you can get those codes and run it by us.

 

this is why i don't drive an old car with high mileage. of course, when i was younger...

 

How many miles on your car? What maintenance have you done to it? If you run out of options, I'm in the Los Angeles area and I can read the codes for you. I don't think the autozone stores in CA will read the codes for you. Some private mechanics don't have the proper code reader to the Prius either.

 

If you were that low on oil, I suspect you will now have pretty high oil consumption from this point on. You likely did some damage.

This is the pattern we've seen here over and over: someone doesn't check their oil regularly and gets intermittent red triangle of death and/or low oil pressure light. Finds it out it's low oil but it's already too late...

 

Well that "engine" light that came on was mostly likely in response to low oil pressure. That is, it actually is the oil light (along with other functions). A lot of people do have problems with the fact there isn't a *specific* oil light on the dash, they see the "engine light" come on but fail to realize the seriousness of it. I am told however that there is a specific oil warning icon on the multifunction display, though you might not have noticed it.

I suspect that you probably were dangerously low on oil. Low enough to increase heat and friction to the point where the engine was not producing sufficient power, leading to other errors. This will have caused at least some degree of permanent wear and damage to the engine. Oil consumption may increase at this point.

Roughly how far below the "low" mark on dipstick was it?

 

There is no low oil shutdown mechanism. It only monitors oil pressure. It did not shut off from low oil unless the oil was so low the engine seized up momentarily. We'll never know because of the no codes read thing.

Now you get to play a guessing game.

 

that's not very low, you probably have another problem that will show up again. hopefully not in an emergency situation.

 

Exactly at the low mark is 2.5 qts left. Not even close to the danger point.

Curious, earlier you said it had just 1 qt. How did you make this assessment?

 

I'm suspecting your car overheated. The coolant might be low in addition to the oil being low. The water pump in the car is known to seep coolant and if seeping long enough, the coolant would become low.

Did you ever do the recall on the inverter pump? That can overheat as well if pump is failing

SM-N900P ?