Check engine light with low (but not empty) gas tank?

[jgrn307]

So the last two fillups on my 2009 Prius (only 3500 miles, the car is nearly brand new) I have had a situation where about 30-40 miles after the car says to fill up, I get the check engine lights all coming on. Both times after I filled up with gas, the lights all went off. The second time I was on the highway and noticed that the gas engine has shut off (at 70mph) and I coasted in on battery power to a gas station. The first time I was in the city, so I may not have noticed if the gas engine has shut off.

Here's the weird thing -- in BOTH situations this occurred only 20-40 miles after the gas warning came on, and in BOTH situations I only needed to put in approximately 9.5 gallons of gas in the car, so this meant I still had a gallon and a half left in the tank at the time of fillup! Why is my car shutting off when I clearly have gas left?

The gas cap was on securely, so that's not an issue. Time for my first warranty repair?

[firepa63]

You ran out of gas. The "guess gauge" in the Prius is not the most accurate of gauges. The bladder in the fuel tank expands and contracts with temperature which compounds the inaccuracy. I suggest that you fill up when you get down to 2 pips. Running out of gas can shorten the life of the traction battery.

[JimboK]

Originally Posted by firepa63

The "guess gauge" in the Prius is not the most accurate of gauges.

Actually, when it flashes it is pretty accurate. It means if you don't get gas now you'll soon run out of fuel.

So Jgrn307, I agree; you ran out of fuel. Though one could make an argument that the fuel bladder design leaves something to be desired (presumably why Toyota left it off the 2010), this is not a defect to be fixed under warranty.

Do a good search here to find out more. There are dozens of discussions on this.

[Jared]

I have often gone 40 miles after the blinking starts and never run out of gas.

[CharlesJ]

Originally Posted by jgrn307

... and in BOTH situations I only needed to put in approximately 9.5 gallons of gas in the car, so this meant I still had a gallon and a half left in the tank at the time of fillup! ...?

The book and Toyota fuel tank capacity is 11.9 gal so you should have had about 2.4 gal left.

[firepa63]

Jared & CharlesJ, as I said, it's a 'guess gauge'. With the bladder you cannot accurately calculate the amount of fuel left in the tank when the last pip starts flashing, nor can you calculate how much fuel you can actually put in each time you gas up. There are tons of post about this subject here on PC.

[Tammy7287]

My question is....why would you wait until 30-40 miles AFTER the gauge says you need gas to actually GET gas? That's just pressing your luck if you ask me.

[patsparks]

Does anyone read the handbook which is in the glove box?
Like all cars it says in the handbook "It is a good idea to keep at least 1/4 of a tank of gas in the gas tank" or words to that affect.
I fill with 2 bars on the gas gauge and still manage to get 50% further on a tank than I did in my Camry.

[richard schumacher]

Originally Posted by CharlesJ

The book and Toyota fuel tank capacity is 11.9 gal so you should have had about 2.4 gal left.

No, sorry. This is another apparent error in the US owner's manual. If the bladder were removed from the tank, the tank might hold 11.9 gallons, but as it is you're lucky if the bladder holds nine gallons.

Anyone who habitually drives after the gas gauge starts to flash will run out of gas sooner or later. It's just a bad idea.

[stevemcelroy]

There are a number of folks who seem to really stretch the distance that they go on a tank - I guess that I do not get it - what's the big deal with stopping for gas before you are running on fumes? A stop at the gas station takes 5, maybe 10 minutes.

I'm actually the opposite - my first car was an old Volvo with a weak fuel pump - if it fell below about 1/3 of a tank the car would shake and buck like crazy - I drove it for 6 or 7 years like this. It has been 15 years or so, but I still find it hard to let the tank get below about 1/4 full.