Gas tank pressue sensor? Huh?

[Grandpa Shooter]

I bought a 2016 Jeep Patriot a month ago to replace an aging HHR.  The check engine light came on and I had it checked out.  The tech called to say it was the gas tank pressure sensor.  What the heck is that and why would it be needed?  This is not a Jeep bashing thread so don't bother.  Why would a vehicle need a pressure sensor?  You put gas in the tank, it gets pulled or pushed to the carburetor, or whatever they call the gas dispersion device these days, and you are off and driving.  Is this one of those we have to clean the air garbage devices the EPA stuck us with?

[Kingcreek]

Yes. Often it’s the seal on the gas cap. I fixed mine by cleaning the gasket and putting a thin film of silicone lube on it. It might not clear the code right away. Sometimes takes a few drive cycles.

[Brad Johnson]

It's part of the evap system. It runs regular neg/pos pressure cycles to check for leaks. Gas caps are a notorious culprit.

Eric O. from South Main Auto has a pretty good overview of how the system work in terms of self-diagnostics. Older vehicle but the basics are sound.
https://www.youtube.com/watch?v=plixTEPXCkY

Brad

[RocketMan]

We also have a 2016 Jeep Patriot, and the gas pressure sensor threw a code for us a while back, too.  Cleaning the gas cap seal fixed the problem.

[Grandpa Shooter]

We also have a 2016 Jeep Patriot, and the gas pressure sensor threw a code for us a while back, too.  Cleaning the gas cap seal fixed the problem.

I was told it is the sensor itself.  The shop got an aftermarket one and it showed up defective and have ordered a dealer item for $7.00 more than the aftermarket.  It also has a clunk in the right front likely a bent tie rod.  I won't know until Monday if they have it fixed or not.  Some repairs are to be expected.  A gas tank pressure sensor was not one I would have thought about.

[Brad Johnson]

How many miles on the vehicle. If memory serves, certain emissions systems components have an EPA-mandated 8/80 warranty independent of any other manufacturer stated warranty. If so, let the dealership deal with it on FCA's dime.

Brad

[Ben]

Some repairs are to be expected.  A gas tank pressure sensor was not one I would have thought about.

Seems from my own experience that from right around the time they started throwing lots of emission controls on vehicles to maybe the early 2000s, if you got a warning light, threw a code, or needed a repair, you could bet on a high chance of it being emissions related. You could also bet on it happening sometime during your vehicle ownership.

I have to say that from around 2010 on, that has not been the case for me. I think no vehicle I have owned of that age or newer has, or has yet, thrown a code for emissions. They must be doing something better than the old days. Not that, obviously from this thread, it doesn't still happen.

[Hawkmoon]

As far as I know, it's not possible to point to the sensor as the culprit, but maybe they added codes between 2000 (my Cherokees) and 2016. The code my wife's Cherokee threw was "Evaporative leak - small." Of course, Jeep didn't sell just the rubber O-ring, so I paid an exhorbitant price for a new gas cap. Since then, I have bought a package of spare O-rings.

If you want to try "fixing" the gas cap, don't use silicone on the O-ring. Other parts of the emissions system don't coexist well with silicone. Use plain old Vaseline.

[Boomhauer]

As far as I know, it's not possible to point to the sensor as the culprit, but maybe they added codes between 2000 (my Cherokees) and 2016. The code my wife's Cherokee threw was "Evaporative leak - small." Of course, Jeep didn't sell just the rubber O-ring, so I paid an exhorbitant price for a new gas cap. Since then, I have bought a package of spare O-rings.

If you want to try "fixing" the gas cap, don't use silicone on the O-ring. Other parts of the emissions system don't coexist well with silicone. Use plain old Vaseline.

A decade and a half makes so much difference in emissions and computer tech it can’t be compared.

We are experiencing this in the machine world as well. A model generation used to be a decade or longer now it’s 2-3 years and the differences are huge

[Grandpa Shooter]

As far as I know, it's not possible to point to the sensor as the culprit, but maybe they added codes between 2000 (my Cherokees) and 2016. The code my wife's Cherokee threw was "Evaporative leak - small." Of course, Jeep didn't sell just the rubber O-ring, so I paid an exhorbitant price for a new gas cap. Since then, I have bought a package of spare O-rings.

If you want to try "fixing" the gas cap, don't use silicone on the O-ring. Other parts of the emissions system don't coexist well with silicone. Use plain old Vaseline.

The initial code indicated a problem with the evaporative system, and when they put it on the diagnostic computer it said the pressure sensor was bad.  That is how they knew the replacement was also bad.  Years ago I had a 1988 YJ that I yanked all the evaporative crap off of, and the carter carburetor along with it.  Put on a replacement carb and went back to points and condenser.  I had it emissions tested just for kicks even though I lived where it wasn't required and the service manager at the shop demanded to know how it could be running so clean.  He even stated the only way it could be cleaner was if it wasn't running at all.  I had changed it over to 2" exhaust pipe and low restriction muffler with no catalytic converter, like the old days.  If they taught mechanics how to properly tune an engine without all the crap I believe we would be better off.  Of course I don't live in a major city, or California either.

[Jim147]

We used to do that with our street rods. They didn't understand a properly tuned engine ran cleaner then a low compression piece of crap.