Some GM vehicle owners may be tempted to overfill their vehicle fuel tank beyond the automatic shutoff point. However, doing so could result in several engine performance issues and fuel system issues, as explained in a recent report.
Per GM TechLink, if the fuel tank is overfilled beyond three clicks past the automatic fuel nozzle shutoff, it’s possible that liquid fuel may enter the evaporative emissions (evap) system vapor lines. In this scenario, the fuel could block the recirculation line and result in fuel tank pressure sensor readings issues.
With regard to 2019 through 2023 Cadillac XT4 models and 2021 through 2023 Buick Envision models equipped with the turbocharged 2.0L I4 LSY gasoline engine, overfilling the fuel tank may result in illumination of the check engine light, as well as diagnostic trouble code (DTC) P0451 (Fuel Tank Pressure Sensor Performance). To note, these vehicles are equipped with a capless refueling system.
If these conditions are found, GM is recommending that a certified GM technician inspect the three vent lines at the fuel tank for damage and remove any contamination present, as well as drain any fuel from the evap vent lines, if needed. Additionally, the vapor lines connected to the evap canister should be disconnected in order to clear any liquid fuel that may be present in the lines. These lines are accessible by removing the right-hand rear wheel and wheel liner. A GM tech will lightly blow shop air into each line in order to clear it of fuel.
Additionally, GM is recommending that customers be reminded not to overfill the fuel tank. Customers shouldn’t “top off” the tank beyond the automatic shutoff point for the fuel station nozzle in order to avoid overfilling the tank. If the tank is overfilled, it could result in the issues outlined above.
To note, these issues are associated with Bulletin #22-NA-203.
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Comments
People have been over filling their tanks for years. Sometimes you can almost get another half a gallon or so. Now they say you shouldn’t over fill because of the crappy capless refueling system which is not secure and hard to refuel your vehicle from a portable fuel can. you have to use the stupid little funnel provided with each vehicle that you have to search for because it’s stowed in different places on different GM vehicles.
Mmmm, didn’t know anything about the funnel, do all GM’s with the capless fueler come with a funnel?
Supposed to. Might be in the glove box or an arm rest. It’s the only way to fill with a gas can.
Has nothing to do with the cap less nozzle. Not overfilling is common knowledge that’s been around for years.
What happens if a defective fuel nozzle doesnt click off and overfills the tank before you can stop it ? I recently had this happen ! can that gas station be liable for the damage ?
Great question, there should be some provision for an overfill that doesn’t require a service visit, that’s just dumb.
Highly likely that one overfill won’t hurt anything. I’m going to guess this is for the people who habitually do it.
I agree. If it happened every time, we would have heard a lot about it a long time ago. Plus, if the nozzle doesn’t shut off and gas gushes all over, you’re not going to try to overfill it -that time. -You’ll be at someone’s throat inside the station. I was anyway.
You people remind me of Dumb and Dumber. That gas nozzle must be clicking off for a reason.
This issue has nothing to do with cap less fill necks it also applies to filler necks with caps. My wife had a 2004 gmc that she tried to pack as much fuel in as possible which sends fuel down to vent tube to the evap system and causes check engine light to come on then long term problem is taking forever to fill your tank because the nozzle keeps clicking off. Don’t be stupid just stop when it shuts off.
Kevin is right on, had this happen to my 2007 Sierra.
Where I live in NJ usually the fuel attendant will round it up I guess he shouldn’t be doing that… But then I have a 2010 Chevy equinox LTZ V6 and I never had this problem. And my wife owns a 2019 Buick Enclave with the capless fueling system and we love it.
Just the lawyers talking. This has been the case since since the first Evaporative Emission Canister on GM vehicles. Early on with Computer Command Control (aka 3C), a DTC would not be thrown and the GM Service Manual simply had a cautionary statement about “Fuel Smell” and waiting for the canister clear. Certain GM vehicles were more sensitive to overfilling than others.
I live on a farm in a very rural area. On the rare occasion when I make a trip to town, if I find fuel priced attractively you bet your backside my tank will be overfilled before I go home. It just the economic reality of needing to make fewer trips to town over the course of a year. Not rocket science.
Apparently not, since you make no sense.
William I also live in the rural area but I don’t over fill my tank so I can get a extra 5 miles I have this new fandango thing called a gas can, you should get one.
Kevin: Point taken, but very respectfully, I have contrary experience. In my both nice, new 1999 Silverado 6.0L and 2000 Silverado 4.8L the “overfill” is about 1 gallon of 87 octane. With the 4.8L, while no torque and no throttle response, that single gallon of low-buck fuel gets me an extra 3.5 more trips to the closest town for farm equipment and/or supplies.
My fuel cans are clearly labeled, used for the farm equipment only, and as such considered a farm expense. That keeps the audit trail clear, clean and accurate, since with farm trucks, mileage is the only deductible item. Nickels and dimes, yes, but that discipline still counts towards the end-of-year-total. Kindly, and with the utmost respect, this is not easily comprehended by the non-agricultural masses.
Actually I do understand your situation, I live on a ranch and have 8 miles of dirt road. I don’t know what evap system the 99 and 2000 has but I do know that the 2004 system will plug up if you continually over fill and I can tell you it is a pain in the butt to remove and clean or you can remove and replace. I have a 1994 dually, big block, that I always over filled and in 267,000 miles never had an issue. Just saying if you move to a newer truck do yourself a favor and don’t over fill or you will be looking at that check engine light and the worst spending 10 to 15 minutes minutes filling up.
Kevin: Thanks much for your insight on trucks newer than mine. I had no idea. I have maintained both the 1999 and 2000 myself for a long, long time and it sounds like I should just hang on to them. I do sincerely appreciate your response. Thanks again, and cheers!
Guess that is GM’s way of saving you about .80 cents on a fillup !
I read a similar article in 1973 when most vehicles had to have gas vapor recovery system where the gas tanks were not to be vented to the atmosphere.
How about if overfilled diesel fuel to my trailblazer duramax 2.5l? I am always top up until full at inlet fuel cap since 2019 but is okay so far none engine notif at dasboard..
For years I have added 2 – 2.5 gallons after the gas pump handle clicks off on my 2014/16/18/20 Grand Caravans and never experienced any problems, other than an additional 40-50 miles of range per tank. And, yes, I know all about the EVAP system having sold carbon canisters to OEMs for many years. Just lucky or smart?
Gm issue not dodge.