gas cap and a trip to Toyota

A loose gas cap has caused a CEL light on many cars, the Prius included. It is not an uncommon thing if that is what you are asking.

Top Five Reasons Your Check Engine Light May Be On

 

too bad you didn't check here first, before wasting your time. and yes, something is definitely fishy.

 

Does not sound abnormal to me. If the CEL light came on in my out of warranty Toyota, it's a minimum $120 diagnostic fee at the dealer. Gas cap is one of the most likely scenarios, so the service advisor is trying to save you some money. If your Prius is still under warranty, then he could've taken the 3 minutes to look up the error code.

 

I've heard/read exactly the same thing that he told you. Think he's on the level.

 

Completely normal. It takes a few "cycles" before the Prius systems realize there is nothing wrong and shut off the light. And yes, a loose gas cap WILL trigger a "CEL". The system can't purge the fuel tank vapours and also get an indication of a leak. If it didn't do this you could have a hose off in the fuel vapour system or even a broken carbon canister and never know it. This would, among other things, be illegal re emissions. It might also be dangerous.

 

Same thing happpened to my dad's 4Runner. The CEL came on and the service advisor tightened the cap and had it reset. He told him to drive it around a few days and see if it comes back on. When it came back on later, they recommended a new gas cap which fixed the problem for a year or two. It came back on earlier this year and they recommended a new charcoal cannister at the tune of around $1k.

 

And the 'few cycles' for the light to go out is not a Prius thing, it applies to nearly all other cars too. I've seen it happen on other cars for other temporary problems (misfire codes on my first Subaru, and unknown electrical problem triggered by freezing fog blowing all night head-on into the grill of a rental car).

 

$100. can buy a lot of peace of mind.

 

It is common for it to reset itself as the service advisor mentioned.

 

Or a lot of lunches if you follow the other advice in this thread.

 

lunch is overrated, if i know stuart, he'd prefer peace.

 

If you're under warranty then they shouldn't charge you. If you're out of warranty then go to your local auto parts store, most of them will read the code for free. It is normal for the light to turn off on its own if the issue has fixed itself.

 

Instead of driving it around for a few days there are a few other things you can do. If the light goes away and doesn't come back, well then there ya go.

Turn the car READY/OFF, READY/OFF, READY/OFF, READY/OFF, READY/OFF, etc. Let it boot up completely and then shut down completely each time. After a few cycles (5 in the Prius maybe? it should clear the CEL unless the code is persistent.

The other sure fire way to clear the code is to disconnect the 12v battery. You lose your radio presets, custom programming like reverse beep and door unlock settings, and you have to reprogram the automatic window settings. But it will clear out everything. If the light comes on after that, there is definitely another problem.

Or you can use a CAN reader/writer to clear the codes, and pull them while you are in there.

And the final option is to do as the dealer suggested and just drive and wait for a bit. Eventually it should go away.

 

I went to my Dodge dealer to have a code cleared, but they said I'd have to book it for a week next Thursday, and quoted me over a hundred bucks. So I went to another dealer, where they went out to the parking lot and did it in less than a minute, and charged me nothing.

Guess which dealer got all my business after that?

 

If your cap was loose he would be right. If it was not loose he is wrong and your light wont go off.

 

What the dealer told you is not fishy. He told you the most common cause of the CEL and sent you on your way.

Most service writers are trained to say "we'll call you when we find out the problem" and making your wallet lighter by $120 while doing it.

 

I thought the engine had to get up to normal temperature to count as a cycle unless the Prius is unique in that regard.

 

You can go to any auto parts store and ask them to read and clear the code.

 

...or look up how to reset it on the web.