(new question - gas cap?) 14 PiP Check Engine Light, P1423 code, gas cap seems tight

Sitting still w no electric miles programming a destination into the NAV, the engine came on, seemed to be a bit rough, and then shut down and showed a Check Engine Light. Wandered over to a dealer the following day and the service writer said "gas cap is loose, the light should go off tom'w". Well, it's a couple of days, 500 miles and 2nd fill of gas tank later and the light is still on.

My OBD-II scanner says P1423.

Also, I filled the gas before the check engine light came on, and I definitely turned until 1 click.

On filling this morning I was surprised that 8.08 gals went in even though the last fuel bar was not yet blinking. [I usually don't get 8 gals in, even w the last fuel bar blinking.] These are different gas pumps, though.

Anyone had any other fuel tank/evap problems with a Nov/Dec built 2014 PiP?

Have app't w dealer on Friday, but don't want to waste everyone's time if it really was a loose gas cap.

How long does it take for the engine light to go off after tightening the gas cap?

Apologies if this is a dup, I searched .

 

You're (all) right! The check engine light went off yesterday morning when I started the car. As much as I remember getting "one click" when I refueled before it went on (and it went on several starts and more than a day later), I'm OK as long as the light is off.

Maybe it takes quite a while to go on, and quite a while to go off. I'm sure someone knows the algorithm, but I was happy enough to cancel the service app't and save everyone's time.

I carry a small volt meter to check battery voltage (which was fine), and I also checked the engine oil (which was full and clean).

 

I've seen the CEL several more times (almost always, I will find the gas cap a bit loose, but not every time). I am quite cautious putting the gas cap on correctly, tightly and one click. I don't fill the gas very often , this seems to happen when I drive over a mountain pass.

At the dealer today for Toyota Care maintenance, and mentioned this. The service writer said ~"the wire that holds the gas cap can get bound up and cause enough tension to loosen the cap", and he basically straightened out what used to be a ~spring/kink in the gas cap tether.

If this is true, there's a safety problem Toyota needs to address. Loosening gas caps = not great.

If this is an end of September "wall job" special, I will be testing this theory by driving mountain passes today and this weekend.

Anyone heard of this?

 

So, this "unwind the gas cap tether" wasn't a failure - I haven't seen the problem since … and I've driven two mountain passes.

BUT, I do think it's a bad gas cap. I can tighten the cap to one click, and sometimes then just pop it off the filler tube. I think the real answer is the user is being much more careful making sure the gas cap is truly seated and not going to pop off. I'll try to get them to replace the gas cap at the next trip to the dealer (which may not be for another 9K miles, as I just did the 20K service, and I think my 2y/24K ToyotaCare is exhausted (??) ). One would imagine this is part of the "emissions system", and covered for a long long time (10y/150K?).

 

tsk tsk …. the Prius info (we) seek is here!

The 2014 list of CARB States in the US | PriusChat

"does include the 150,000/10 year duration"