Check Eng Light & Loose Fuel Door?

At 18K miles on our 2015 Prius v model 5, the check engine light came on. Toyota said it was probably a loose fuel cap & reset the codes. I always try to do 2 clicks on the fuel cap. The check engine light came on about 2-3 weeks after last fill up with about 1 bar on the fuel gauge. I did get gas just before taking it to Toyota, and the check engine light stayed on, until reset by Toyota. The problem has not come back after about 200 miles on the current tank.
Any other experience with this fuel cap problem? Software problem?

 

Down to 3 bars full on the tank & the check engine light has stayed off, since reset by dealer!
Checked our Prius v 2015 Quick Reference Guide & page 8 says "NOTE: Tighten (Fuel Tank Cap) until one click is heard. If the cap is not tightened enough, Check Engine indicator may illuminate." Also section 4-4 page 207 of our 2015 Owner's Manual says "After refueling, turn the fuel tank cap until you hear a click. Once the cap is released, it will turn slightly in the opposite direction."
So the click is real & a loose cap can cause the check engine light to come on. Not sure if the light will reset itself after the cap is tightened to one click or can only be reset by dealer??

 

Thanks Bisco, but given the more serious "Check Engine Light" potential problems, e.g. "malfunction of hybrid, electronic engine control &/or electronic throttle control systems" stated in 8-2 of 2015 Owner's Manual, and the instruction to "Have the vehicle inspected by your Toyota dealer immediately.", it does not seem wise to wait to see if the light goes off by itself.
In our case, after the light came on, we did 5 short separate trips in the car over 1 day & the light stayed on, including after refueling on the way to the dealer for reset.

 

Thanks pointing us to the additional words, which are on p494 section 8-2 of our 2015 Prius v manual, which follow the "Warning Light and buzzer list" p488-494. It would make more sense to us, if Toyota had put the possible loose fuel cap cause & suggestions directly in the "Malfunction indicator lamp" block p489 in the list/table, rather than following the table on P494 or at least reference p494 in the list/table.
In any event Toyota's loose cap/low fuel advice on P494 to drive the car for several trips to see if the the Malfunction indicator lamp goes off before taking the car to the dealer directly contradicts the advice in Malfunction indicator lamp block on P489 to have the car inspected immediately by the dealer.
Also, above the Warning light and warning buzzer list p488 2015 Prius v manual, it says "If a light comes on or flashes, but then goes off, this does not necessarily indicate a malfunction in the system. However, if this continues to occur, have the vehicle inspected by your dealer."
As stated in our prior posts our Malfunction indicator lamp/Check Engine light came on, stayed on solid/did not flash, even after refueling just before taking it to the dealer. What are the risks to the car/driver if the Malfunction Indicator lamp is really a malfunction of the Hybrid System, Electronic Engine Control System or Electronic Throttle Control System as stated in the list on P489 and not a loose fuel cap or low fuel?

 

Thanks Mike. The check engine light in our experience with other cars requires taking the car to the dealer quickly/immediately as stated in the Warning Light & Buzzer list/table p489 in our 2015 Prius v manual, i.e. hybrid, engine &/or throttle control malfunctions. The loose gas cap/fuel tank empty problem should not trigger the check engine light/malfunction indicator lamp, and have a unique warning light/lamp, since the advice (on p494 after the Warning Light list) is to tighten the cap, drive for several trips & see if the warning light goes off, before going the dealer. When we went to the dealer, they said that the problem was probably a loose gas cap before even looking at the codes.