A few weeks ago, I drove my car into Manhattan for a concert. I parked in a typical multi-floored parking garage that requires a car elevator in order to maximize the space available. All the cars are valeted by the attendants.
When I arrived there were about 3-4 cars waiting to depart and I was behind at least 5 waiting to be parked. The attendant came by, gave me my ticket so that I could be on my way, and said “leave the car on and the keys inside.” I said ok, but then noticed my fuel level was slightly below 1/4, although plenty to get me back home later. But with the backup of cars, I was concerned it would be idling for a long time wasting gas, so I turned it off. I went back and told the attendant that I turned it off since the fuel was low, and he was fine with that.
After the show, I went back to pick the car up. It came out and I was on my way, but then noticed the “check emission system” sign on my dashboard. The car was running fine, but the sign stayed on for the duration of my 30-minute drive.
The next morning, I ran some errands and the sign turned back on after a few minutes of driving. When I finally went for my fuel fill up, it went away and hasn’t turned back on again. So what could be the reason for the sign turning on?
My first thought was the fuel cap, which might suggest that the garage was stealing gas from cars. But even if it engaged in such activities, why would they do it from a car already low on gas? Perhaps there is more obvious explanation? I’ll add that I have many gas stations near me, so my fuel level gets very low often, and the sign has never turned on in the past.
The sign means that the car is unable to optimize the gas/air mixture to produce the lowest possible emissions under the driving conditions.
There are a lot of reasons for that, but it could be as simple as replacing your air filter (or banging out the one you have and reusing it).
It also could mean that the engine was flooded because it was turned off and on several times in a short amount of time, which could have happened it the valets turned your car on every time it needed to be moved up in the line, and then turned it off again. By the way, that actually uses more fuel than just leaving it on, because it takes a jolt of extra gas to start the car.
I don’t know how your car’s warning system works, but sometimes when it registers a code, but the problem goes away, it continues to store the code for a while. How it gets cleared depends on the car, but it likely doesn’t happen as soon as the problem goes away, so if it were flooded, and cleared the extra gas in a few minutes, it could still have held the code.
But there are other things that could trigger the emissions code-- your catalytic converter may not be operating properly, or you could have a sticky fuel injector. It may have nothing to do with the valet parking, albeit, in my experience, cars do have a tendency to flash the emissions warning (or the “check engine” light) when the idle for a long time, especially in traffic, because it’s more difficult for the car to adjust the mixture under that condition.
Thanks. The quoted part sounds very plausible. If it were on ongoing issue, then I would definitely take it to the mechanic, but it never happened before or after the 12 or so hours that I described.
I personally have a code reader myself, but if you go down to Autozone and the like, they can tell you what the fault code was.
It’s a service that they provide for free, since they are hoping that you will buy whatever parts you need to fix it from them.
Some of the codes are pretty self-explanatory, but others can be a bit cryptic. Some aren’t as straightforward as they seem. For example, the “gas cap” code really means there’s a leak in the vacuum system that is designed to keep gas fumes inside the vehicle. It might be as simple as a loose gas cap, or it might be a leak anywhere else in the system. It might even be a faulty vacuum pump.
Once you get the code, post it here and we can tell if it’s something you need to worry about or not.
Oh, by the way, if it’s a loose gas cap, spend the money on the one from the dealer. We lost a gas cap once (our negligence), and bought a generic one for $4. It didn’t clear the code, and also triggered something that happens when a code is held for a certain amount of time-- it made the cruise control non-function.
So we bought the $15 cap from the dealer, and they cleared the code and restored the cruise control (a free service when you buy a part or have work done). They have a device that does it immediately.
No more problems.
I don’t think the car really “knew” it had a generic cap. I think it just didn’t give a tight enough seal.
All the car knows is that there is a leak. It might not even be the gas cap.
If tightening the gas cap or replacing the gas cap with the proper cap doesn’t fix it (as you said, spend the money on the one from the dealer), finding the leak can be a royal pain in the backside. The leak can be anywhere in the system (fuel filler tube, any of the evap hoses, cannister or any of its connections/hoses, etc).
There is a “check engine light” denoting that a stored engine fault code has been stored and on my car a separate “check gauges” light that tells me to look at the gauges display to see if maybe it is low on gas, oil, power, or something else that would be shown on the instrament panel.
It is possible that your car does not have a separate check engine and check gauges light, so the light went off when you filled with gas. And it could just be the gas cap wasn’t on right and when you filled up it solved the problem. These sensors require a couple of cycles to reset so they don’t automatically reset once the problem is fixed. .
A bit of an oversimplification, as there are many things that can trigger an emissions-related check-engine light. Misfire or incomplete combustion is one reason (the ECM can identify unexpected fluctuations in engine RPM related to this). Loss of catalytic converter efficiency is another (not enough difference in exhaust O2% between measurements upstream and downstream of the cat). And as the OP notes, a leak in the evaporative emissions system is another. This can be just a loose fuel cap, in which case the code often goes away on its own after a few more key-on cycles if you snug up the cap. But it could also be a real leak somewhere else in the system. Example, several years back, I had a crack in a molded plastic boss on my evaporative emissions recovery cannister, necessitating replacement.
Yes, but I was trying to keep my answer to a reasonable length. I didn’t want to list every part that could produce the light, nor how much of a problem each one might be.
What type of car do you have? Some older Chrysler products (mid 1990s-2010s?) you can turn the key on/off/on in a certain sequence and the code will be displayed in the odometer reading.
Most cars have that feature. You have to Google the on/off sequence (you don’t have to start the engine, just turn the key from off, to the position where it lights up the dash, and lets you operate the radio), then once you get the code, Google the code. If you don’t have a reference manual.
Every car I’ve owned with a digital odometer has had this feature.
Not in any car made in the last decade.
It’s pretty much impossible to “flood” a fuel-injected car, unless there is a really serious ignition problem, which would be obvious. As for taking more fuel to start, that’s also not true anymore.
OK, not flooded in the classic sense, but there could be gas fumes in the throttle that throw off the car’s computer as it tries to control the gas/air mixture.
And I don’t know how old the OP’s car is. It could be old enough that turning it on and off wastes gas.
This is an issue of sometimes getting what you pay for. Parts from 3rd-party manufacturers are not always to the same standards as OEM parts–they will work, but not as well, or maybe wear out sooner.
In modern cars it only takes about 10 seconds worth of idling to match the amount of fuel during startup. Even on older carbureted engines it was only 30-60 seconds. Kinda like the myth about leaving the lights on to save electricity. I think the worst startup current for your typical indoor light is with older style fluorescent tubes, and even that is still only equivalent to about 30 seconds of continuous running. So turn them off.