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I have had the check engine light come on twice now.

Any help is appreciated. Here is the full story.

At approx 1,100 miles, the check enging light came on. Took to
dealer. They told me it was code P1455 on the diagnostic computer,
meaning "vapor reducing fuel tank system malfunction". The
technician said no one at the dealer had ever seen this code appear
before. He said that the check engine light has come on for some
Prius owners when the gas cap has not been properly re-tightened
after removal (as when filling the tank).

They ran through their manual's entire troubleshooting procedure.
None of the procedural checks found a problem. Then, they "cleared"
the computer and restarted the car. The light did not stay on. So,
the immediate problem is "solved" (I guess/hope). They said that if
it happens again, they'll contact Toyota and pursue further.

Well, the same thing just happened tonight - two weeks after the first time. Each time this happened two days after filling the tank. And, yes, when I filled the tank this last time, I was absolutely sure that I seated the gas cap properly.

I have heard of other cars, Toyota and non-Toyota, having
diagnostic lights come on when the gas cap was not "properly" seated.

The technician also said that if the light comes on and you discover
that the cap was not seated, then you re-seat it properly, the light
will not go away "right away" - you need to drive it for at least 20
minutes.

Any relevant experiences from you all would be appreciated.
 

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The vapor recovery system basically sucks up the fumes from the gasoline when refilling the tank. There is a canister on-board that holds the fumes and dispenses it in the fuel system when starting your vehicle (at least for the GM vehicles I have experience with). If it were not for this vapor recovery system, no petrol combution vehicles would be PZEV certified.

A malfunction of this system should not affect driving performance or dynamics. It is merely something used to prevent gasoline vapor from entering the atmosphere when filling your tank. I will not tell you what to do, but assuming that you purchased a Prius to help protect the environment, you should get this fixed before it weighs on your consciousness. I wouldn't allow the dealership to tell me that they can't fix this problem, which should be covered under warantee.
 

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Re: Check engine light - code P1455 - vapor reducing fuel ta

When I see "vapor reducing fuel tank system malfunction" I think about the bladder inside the tank that inflates to reduce volume that could be consumed by vapor.

fyaeger said:
I have had the check engine light come on twice now.

Any help is appreciated. Here is the full story.

At approx 1,100 miles, the check enging light came on. Took to
dealer. They told me it was code P1455 on the diagnostic computer,
meaning "vapor reducing fuel tank system malfunction". The
technician said no one at the dealer had ever seen this code appear
before. He said that the check engine light has come on for some
Prius owners when the gas cap has not been properly re-tightened
after removal (as when filling the tank).

They ran through their manual's entire troubleshooting procedure.
None of the procedural checks found a problem. Then, they "cleared"
the computer and restarted the car. The light did not stay on. So,
the immediate problem is "solved" (I guess/hope). They said that if
it happens again, they'll contact Toyota and pursue further.

Well, the same thing just happened tonight - two weeks after the first time. Each time this happened two days after filling the tank. And, yes, when I filled the tank this last time, I was absolutely sure that I seated the gas cap properly.

I have heard of other cars, Toyota and non-Toyota, having
diagnostic lights come on when the gas cap was not "properly" seated.

The technician also said that if the light comes on and you discover
that the cap was not seated, then you re-seat it properly, the light
will not go away "right away" - you need to drive it for at least 20
minutes.

Any relevant experiences from you all would be appreciated.
 

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Re: Check engine light - code P1455 - vapor reducing fuel ta

Well, the same thing just happened tonight - two weeks after the first time. Each time this happened two days after filling the tank. And, yes, when I filled the tank this last time, I was absolutely sure that I seated the gas cap properly.
I read something, SOMEWHERE... there's been so many prius pages I've read. :p Butt I read that if you don't fill it up with REGULAR UNLEADED gasoline (87 octane) it was likely to make some kind of warning light come on about vapors or emissions or something like that.

Could that be the case? What are you filling your tank with?
Also, it sounded like there's a chance you weren't sure what "properly seated" meant. On the inside of the door of your gas cap, it mentions that you need to twist til it makes a couple snaps, so that it's totally closed. Otherwise a system light will come on.

Hope some of this may have helped, and perhaps someone else read something regarding gas above 87 octane and the warning lights?
 

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Re: Check engine light - code P1455 - vapor reducing fuel ta

bradca21 said:
I read that if you don't fill it up with REGULAR UNLEADED gasoline (87 octane) it was likely to make some kind of warning light come on about vapors or emissions or something like that.
[...]perhaps someone else read something regarding gas above 87 octane and the warning lights?
We'd love to see an explicit reference. I've been using nothing but 92 octane and have had no such problem; the owners manual makes no warning against using higher octanes.
 

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Re: Check engine light - code P1455 - vapor reducing fuel ta

richard schumacher said:
bradca21 said:
I read that if you don't fill it up with REGULAR UNLEADED gasoline (87 octane) it was likely to make some kind of warning light come on about vapors or emissions or something like that.
[...]perhaps someone else read something regarding gas above 87 octane and the warning lights?
We'd love to see an explicit reference. I've been using nothing but 92 octane and have had no such problem; the owners manual makes no warning against using higher octanes.
The owner's manual states 87 octane (R+M/2).

There have been several reported cases of Check Engine lights in the classic Prius by using the higher-octane fuels. (usually engine-misfire codes - the atkinson cycle engine doesn't like the later detonation time of the higher octane). The 2004 Prius has the same engine as the classic Prius, so... (see page 202-203 of the 2004 US Prius Owner's Manual.)

There's no reason to use higher octane fuel in a car that doesn't require the higher octane (is knocking, or the owner's manual requires it), unless you like paying more for gasoline, or your local higher-octane fuel contains less sulfur than the regular.
Here's what the US Federal Trade Commission has to say:
http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm

The Low-Down on High Octane Gasoline
Are you tempted to buy a high octane gasoline for your car because you want to improve its performance? If so, take note: the recommended gasoline for most cars is regular octane. In fact, in most cases, using a higher octane gasoline than your owner's manual recommends offers absolutely no benefit. It won't make your car perform better, go faster, get better mileage or run cleaner. Your best bet: listen to your owner's manual.

The only time you might need to switch to a higher octane level is if your car engine knocks when you use the recommended fuel. This happens to a small percentage of cars.

Unless your engine is knocking, buying higher octane gasoline is a waste of money, too. Premium gas costs 15 to 20 cents per gallon more than regular. That can add up to $100 or more a year in extra costs. Studies indicate that altogether, drivers may be spending hundreds of millions of dollars each year for higher octane gas than they need.

What are octane ratings?
Octane ratings measure a gasoline's ability to resist engine knock, a rattling or pinging sound that results from premature ignition of the compressed fuel-air mixture in one or more cylinders. Most gas stations offer three octane grades: regular (usually 87 octane), mid-grade (usually 89 octane) and premium (usually 92 or 93). The ratings must be posted on bright yellow stickers on each gasoline pump.

What's the right octane level for your car?
Check your owner's manual to determine the right octane level for your car. Regular octane is recommended for most cars. However, some cars with high compression engines, like sports cars and certain luxury cars, need mid-grade or premium gasoline to prevent knock.

How can you tell if you're using the right octane level? Listen to your car's engine. If it doesn't knock when you use the recommended octane, you're using the right grade of gasoline.

Will higher octane gasoline clean your engine better?
As a rule, high octane gasoline does not outperform regular octane in preventing engine deposits from forming, in removing them, or in cleaning your car's engine. In fact, the U.S. Environmental Protection Agency requires that all octane grades of all brands of gasoline contain engine cleaning detergent additives to protect against the build-up of harmful levels of engine deposits during the expected life of your car.

Should you ever switch to a higher octane gasoline?
A few car engines may knock or ping - even if you use the recommended octane. If this happens, try switching to the next highest octane grade. In many cases, switching to the mid-grade or premium-grade gasoline will eliminate the knock. If the knocking or pinging continues after one or two fill-ups, you may need a tune-up or some other repair. After that work is done, go back to the lowest octane grade at which your engine runs without knocking.

Is knocking harmful?
Occasional light knocking or pinging won't harm your engine, and doesn't indicate a need for higher octane. But don't ignore severe knocking. A heavy or persistent knock can lead to engine damage.

Is all "premium" or "regular" gasoline the same?
The octane rating of gasoline marked "premium" or "regular" is not consistent across the country. One state may require a minimum octane rating of 92 for all premium gasoline, while another may allow 90 octane to be called premium. To make sure you know what you're buying, check the octane rating on the yellow sticker on the gas pump instead of relying on the name "premium" or "regular."

For More Information
If you're concerned about the accuracy of an octane label - or if you don't see a yellow octane sticker on a gasoline pump, write: Consumer Response Center, Federal Trade Commission, Washington, DC 20580.

The FTC works for the consumer to prevent fraudulent, deceptive and unfair business practices in the marketplace and to provide information to help consumers spot, stop and avoid them. To file a complaint or to get free information on consumer issues, visit http://www.ftc.gov or call toll-free, 1-877-FTC-HELP (1-877-382-4357); TTY: 1-866-653-4261. The FTC enters Internet, telemarketing, identity theft and other fraud-related complaints into Consumer Sentinel, a secure, online database available to hundreds of civil and criminal law enforcement agencies in the U.S. and abroad.

October 2003
 

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Re: Check engine light - code P1455 - vapor reducing fuel ta

mrv said:
richard schumacher said:
bradca21 said:
I read that if you don't fill it up with REGULAR UNLEADED gasoline (87 octane) it was likely to make some kind of warning light come on about vapors or emissions or something like that.
[...]perhaps someone else read something regarding gas above 87 octane and the warning lights?
We'd love to see an explicit reference. I've been using nothing but 92 octane and have had no such problem; the owners manual makes no warning against using higher octanes.
The owner's manual states 87 octane (R+M/2).
Yes, as the *minimum* acceptable octane. Nowhere does it state not to use a higher octane.


There have been several reported cases of Check Engine lights in the classic Prius by using the higher-octane fuels. (usually engine-misfire codes - the atkinson cycle engine doesn't like the later detonation time of the higher octane). The 2004 Prius has the same engine as the classic Prius, so... (see page 202-203 of the 2004 US Prius Owner's Manual.)

There's no reason to use higher octane fuel in a car that doesn't require the higher octane (is knocking, or the owner's manual requires it), unless you like paying more for gasoline, or your local higher-octane fuel contains less sulfur than the regular.
Lower sulfur is why I use it. If Toyota ever says not to, then I'll stop.


Here's what the US Federal Trade Commission has to say:
http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm

[Excellent citation elided; see previous.]
 

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MY check engine light went on for the second time, too

I just came back from a futile trip to the dealer - b/c my check engine light went on again. It went on about 2 days after I rec'd the car (4/22/04), and it was checked by the ONE Prius guy at the dealer - and supposedly something was reset (they probably just turned off the light!).

This morning, while on the highway, it came on again - so I drove to the dealer - and this time, I was told that I had to replace something - they were very, very unclear about what exactly needed to be replaced (the exhaust was mentioned). Apparently, I am polluting the air as i drive my defective Prius around town.

The part had to be ordered - so who knows when it'll come in. My car will be laid up for a day - but I'm worried that it'll become more defective once they fiddle with things.

Aargh.
 

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P0136 and/or P0138 (check engine light on new 2004 Prius)

It's not uncommon for 2004 Prius to exhibit a check engine light in the first couple hundred miles. If the above codes trigger it, it's probably the O2 sensors picking up some normal stuff burning off of the exhaust system. Basically, drive the 2004 Prius on the highway for a bit to complete the burn-off, and you'll be all set - most likely no need to replace the O2 sensors.

(My 2004 had the check engine light come on twice within the first 200 miles, both codes cleared themselves after more driving.)

Attached is the Technical Service Bulletin for this particular check engine scenario: TSB EG018-03
 

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Thanks for the Service Bulletin Info - BUT...

I downloaded your attachment and tried to understand what the service bulletin was talking about - and I'll bring it with me to the Prius repair guy next week (it is always good to come across as informed, in my opinion)...BUT...even though I have 700+ miles on this car (minimal, I guess) - I'm worried about driving it since "they" told me that they were ordering an all-important part (again, something to do with the exhaust). I'd hate for there to be a meltdown on the road - since ordinary citizen repair guys don't know how to turn on the car, let alone fix it.

I'm just wondering why this particular car is having problems so quickly. I understand the first burn-off problem - but why the second? Is there a recall or alert on this problem...b/c they made me feel like I was the first on my block to have such a problem.

Sharron
 

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Check Engine light on during first few hundred miles

My Check Engine light was on for the first few hundred miles after buying my 2004 Prius, and here's what I heard from a reliable service source, who has seen this on all the 2004 models:

There is a coating on a manifold that "needs to be" burned off. While it is burning off, it makes the emission control system think that emissions are out of range, causing the Check Engine light to come on. When the coating is burned off (my finished at 310 miles), the light should go out. Two caveats, however:

1. If the Check Engine light is on for any reason, the car enters a fuel-enriching "fail-safe" mode, which reduces your gas mileage signicantly. There is no reason to enrich the fuel mixture for this particular condition (emissions out of range), but the computer isn't that smart, so it does this for any Check Engine condition.

2. Once the Check Engine light has come on, the computer has to see SEVEN cold engine starts without the offending condition before it will turn off the Check Engine light.
 

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Speaking of Octane: I would love to be able to fill up with 87, but most of the stations I go to have 82, 85, 90 (or some combination like that). Never a nice 87, but that stupid 85 is around everywhere, then the big 90. In my truck I bit the bullet and put in the 85, and I did get pinging. I'll probably bite the money bullet and go to the 90 since it's only 8 gals ( I can afford the extra $2).

Anyone ever able to find that perfect 87? I live in Denver Colorado. Do I just shop at the "bad" gas places? Thanks
 

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You might want to check with your service dept. to be sure, but I believe 85 is considered ok in the Prius for driving in Denver. There's a lot less air available, so less mixture in the cylinders which lowers the chance of predetonation enough that 85 works ok. If your truck had high compression cylinders or was built prior to computerized fuel injection and predetonation detectors, you can probably discount it's pinging when trying to predict your Prius' behavior.

Of course, if you're planning to head down to lower altitudes, fill up with 90 octane prior to leaving. A half tank of 90 mixed into a half tank of 85 would probably be higher than 87.
 

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ephrumsirc,
Here in N. Florida, I have only seen 87 octane rated regular gas....haven't experienced the 85 octane at all....
 

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ephrumsirc said:
Speaking of Octane: I would love to be able to fill up with 87, but most of the stations I go to have 82, 85, 90 (or some combination like that). Never a nice 87, but that stupid 85 is around everywhere, then the big 90. In my truck I bit the bullet and put in the 85, and I did get pinging. I'll probably bite the money bullet and go to the 90 since it's only 8 gals ( I can afford the extra $2).

Anyone ever able to find that perfect 87? I live in Denver Colorado. Do I just shop at the "bad" gas places? Thanks
You are in a high altitude area, therefore the octane is reduced because of the reduced oxygen present as well as the reduced atmospheric pressure, both resulting in a need for less octane to do the same job (less air pressure results in less filling of the combustion chamber during intake and less oxygen further reduces the likelihoold of pre-ignition, aka knock). If you have any issues with using 82 octane, you should be fine with 85, the midgrade for your area. The car should run fine on 82 octane however, unless you end up driving in lower altitude areas, in which case you will need to add gas of a higher octane to meet your engine's needs. Higher octane than you need will generally make the engine run worse as altitude increases, not better.
 

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Check engine light = bad gas tank?

My check engine light went on 2 days after the auto shut-off failed at my corner gas station. I called up my dealer & he said to check my gas cap. I told him that I had and that it was just as tight as it always is. He said that the check engine light would clear after I had started & driven the car "about 15 times." I said OK, and that I would call back in 2 weeks or so.

Well, the light never went off. I took it in yesterday to have them run the codes... where I was informed that my warranty had expired this month & I would have to pay for them to find out what the light was about. :x I was NOT pleased, had I taken it in when it first went on, the car would still have squeaked in under 36 months.

P1455. Vapor pressure loss... requiring a new fuel tank and canister. The service manager ordered the parts & decided that it should be replaced under warranty, so no charge to me.

~Sage

Silver '01 with 31,000 miles
 

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mdacmeis said:
...because of the reduced oxygen present as well as the reduced atmospheric pressure, both resulting in a need for less octane to do the same job...
Hmmm... something to keep in mind if my wife or I ever end up in that situation; probably won't, but still good info. :)
 

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Re: Check engine light - code P1455 - vapor reducing fuel ta

I own two Toyota's, a 2002 Prius and a 1998 Camry. The Camry has had the check engine light come on only twice and both were defective gas caps. The first one cost me $120 ($85 for the diagnostics check, $20 for the gas cap, and the balance for tax and environmental fee). The second one cost $6.99 at AutoZone.

I think there may be a weakness in the Toyota gas cap design. The $6.99 gas cap is a lot cheaper, and a possibly quick and inexpensive, shot-in-the-dark fix.

You might want to try it before you spend a lot of money (unless it is covered under warranty, of course).
 
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