Check engine light came on because of loose gas cap (I thnk), it will not go off

Avoidin Deer

Zoom Zoom, baby
Contributor
:
Central Virginia
:
2019 CX-5 Reserve
I searched to see if this had been answered before (I gotta believe it has been) but found no matches.

This is a 2019 GT Reserve with less than 3,000 miles on it.

Last night I went out to dinner. I got in my car and started driving home, and about 1 mile down the road the Check Engine light came on. When I got home and looked, the gas cap was completely off, just laying there. I only had about 1/4 tank of gas left, so don't know why the Check Engine light had not lit sooner. I don't think anyone messed with the car, because I always lock my car. I can only assume I did not tighten it and it somehow unscrewed all the way without the Check Engine light coming on. (I'm still trying to replay events in my mind that may have caused this.)

So I put the cap back on last night and drove 8 miles to the gas station this morning. The light did not go out during this trip. I filled the tank and drove 8 miles back home. The light still did not go out.

Is there a way for me to reset the Check Engine light without an OBD2 reader?
Should it have gone out (might it go out) on its own? This is a really stupid thing to not self-reset.
 
Gas cap might have been only part of the problem?
 
Gas cap might have been only part of the problem?

That's what I'm worried about. But it would be a heck of a coincidence on a low-mileage car.

Do you know if the C.E. light self-clears after a while when caused by a loose gas cap that's been fixed? It would be strange (but not impossible) for this to require a dealer visit.
 
I'd run to town and get an OBD reader first, just to know. You know you want one to play with anyway!
But if the dealer's not too inconvenient... oh wait, that's unlikely.
 
I'd run to town and get an OBD reader first, just to know. You know you want one to play with anyway!
But if the dealer's not too inconvenient... oh wait, that's unlikely.

Funny you should mention that...

I was on Walmart and Advance Auto websites looking at the readers they have. But I'd really rather have one of the Foseal units and buy a used smartphone (or maybe even a notepad) so I could have a full complement of gauges.

And yeh, the dealer is about 30-45 minutes away, but I've thought of going there anyway to have the infotainment system firmware updated, since my XM issues have not abated. Maybe I can get an MX-5 for the day!
 
if issue (whatever it was) is self resolved it should automatically turn off the check engine in about 6-7 engine on/off cycles or trips.
 
From my '16 manual:

If the check fuel cap warning light illuminates, the fuel-filler cap may not be properly installed. If the warning light illuminates, park your vehicle safely off the right-of-way, remove the fuel-filler cap and reinstall it correctly. After the cap has been correctly installed, the fuel cap warning light may continue to illuminate until a number of driving cycles have been completed. A drive cycle consists of starting the engine (after four or more hours with the engine off) and driving the vehicle on city and highway roads. Continuing to drive with the check fuel cap warning light illuminated could cause the check engine light to illuminate as well.

I assume your '19 is similar. The surprise for me is the 4 hours off requirement for the drive cycle.
 
Funny you should mention that...

I was on Walmart and Advance Auto websites looking at the readers they have. But I'd really rather have one of the Foseal units and buy a used smartphone (or maybe even a notepad) so I could have a full complement of gauges.

And yeh, the dealer is about 30-45 minutes away, but I've thought of going there anyway to have the infotainment system firmware updated, since my XM issues have not abated. Maybe I can get an MX-5 for the day!
You can always go to AutoZone having a free CEL code read to verify what is the true cause of the CEL. They'll provide you a print out with error codes, as well as a list of things you can do to fix the problem. They can also do a reset to force the CEL off, instead of waiting for a certain on/off cycles to turn off the CEL by itself, assuming the loose gas cap is the only problem in your situation.
 
From my '16 manual:



I assume your '19 is similar. The surprise for me is the 4 hours off requirement for the drive cycle.

Thanks for that. My '19 only has Check Engine light, with no separate fuel cap warning.

I have not just sat in the thing and started/restarted. And the 4 or so trips I've taken have been short hops in between stores while shopping. So by that "4 hours off" requirement," I've only made 2 cycles.

I was shocked when it did not immediately go off when I put the cap on, and even more shocked when it did not go off when I filled the tank. But I've never had the cap come off before on any car. The 2019 manual is silent on this issue.
 
Thanks for that. My '19 only has Check Engine light, with no separate fuel cap warning.

I have not just sat in the thing and started/restarted. And the 4 or so trips I've taken have been short hops in between stores while shopping. So by that "4 hours off" requirement," I've only made 2 cycles.

I was shocked when it did not immediately go off when I put the cap on, and even more shocked when it did not go off when I filled the tank. But I've never had the cap come off before on any car. The 2019 manual is silent on this issue.

If you lived in NJ or OR, you could blame it on the attendant who filled your tank. :)
 
You can always go to AutoZone having a free CEL code read to verify what is the true cause of the CEL. They'll provide you a print out with error codes, as well as a list of things you can do to fix the problem. They can also do a reset to force the CEL off, instead of waiting for a certain on/off cycles to turn off the CEL by itself, assuming the loose gas cap is the only problem in your situation.

Funny, I stopped by Advance Auto this morning and the thing threw 3 codes, all related to the loose cap. I had to look the codes up when I got home, they could not tell me what they meant.

They told me that they are no longer allowed to reset the CEL. Sounds like a policy driven by a lawsuit. I wonder if their inability to interpret codes are likewise driven.

At least I know there's nothing really wrong. If the advice given a couple of comments up does not work, I'll disconnect the battery for a while or swing by the station I use for my truck repairs and beg a favor.
 
If you lived in NJ or OR, you could blame it on the attendant who filled your tank. :)

I gotta tell you, I have never done that before, and I've been driving for nearly 50 years. And how could I burn through 3/4 of a tank of gas like that before the CEL went on???

But if I lived in NJ, I'd have other things to bltch about.;) I've never been to OR.
 
I gotta tell you, I have never done that before, and I've been driving for nearly 50 years. And how could I burn through 3/4 of a tank of gas like that before the CEL went on???

But if I lived in NJ, I'd have other things to bltch about.;) I've never been to OR.

I'm not pointing fingers or anything, and can't answer those questions, but... how could it happen?

And remember, there are plenty of beautiful areas in NJ. And then there's NoVa, where I lived many years ago, and which I've heard you comment upon, not too lovingly... :)

Never been to Oregon? ROAD TRIP!!!!!!
 
I'm not pointing fingers or anything, and can't answer those questions, but... how could it happen?

A friend used to tell me that everything before the "but" is BS ;) It cracks me up every time I catch myself doing it.

And I've been to western NJ (Delaware Water Gap parts), as well as the congested parts of the state (Edison/Newark). Funny how some states can be night & day with only a couple hours drive. Oregon is one place I have never been, either business or pleasure. Maybe I should take a road trip, and you guys can show me how to pump gas!
 
A friend used to tell me that everything before the "but" is BS ;) It cracks me up every time I catch myself doing it.

And I've been to western NJ (Delaware Water Gap parts), as well as the congested parts of the state (Edison/Newark). Funny how some states can be night & day with only a couple hours drive. Oregon is one place I have never been, either business or pleasure. Maybe I should take a road trip, and you guys can show me how to pump gas!

Well then, what's your gas cap theory?
 
Well then, what's your gas cap theory?

Well, since it was down to 1/4 tank before the CEL went on, and the cap was completely off, I'm mildly concerned that someone messed with my car. But there's nothing else wrong. And other than when I'm at home (with no other humans around), I keep it locked by habit. I can't imagine someone doing something like that, but I'm still mildly concerned about it being a possibility.

Obviously, the only logical thing is that I left it off or I left it loose and it jiggled completely undone. I just can't wrap my head around going 10 days like that before the light went off.

I guess life is good if this is all I have to fret over. If it were my 15 year old truck I'd just shrug it off.
 
Well, since it was down to 1/4 tank before the CEL went on, and the cap was completely off, I'm mildly concerned that someone messed with my car. But there's nothing else wrong. And other than when I'm at home (with no other humans around), I keep it locked by habit. I can't imagine someone doing something like that, but I'm still mildly concerned about it being a possibility.

Obviously, the only logical thing is that I left it off or I left it loose and it jiggled completely undone. I just can't wrap my head around going 10 days like that before the light went off.

I guess life is good if this is all I have to fret over. If it were my 15 year old truck I'd just shrug it off.

Smokey Bear? Rocky Racoon?

There is no doubt that I would be capable of leaving it off!

Where do you put the cap while you're pumping? Hooked to the door, lying next to the filler, on the pump, or on the roof? [don't laugh, I've seen people do it]. It doesn't seem possible that it could vibrate loose.

Not that any of this matters. The CEL delay, however, might. No luck interpreting the codes?
 
Smokey Bear? Rocky Racoon?

There is no doubt that I would be capable of leaving it off!

Where do you put the cap while you're pumping? Hooked to the door, lying next to the filler, on the pump, or on the roof? [don't laugh, I've seen people do it]. It doesn't seem possible that it could vibrate loose.

Not that any of this matters. The CEL delay, however, might. No luck interpreting the codes?

Hey hey HEY!!!! Let's not get smart. ;) And I hadn't thought of that...I DO have bear on the property, as well as very aggressive raccoon. They fear nothing.

I agree that none of it matters now, but your comment got me thinking. I just went outside and checked (even though I got bear hanging around and it's dark)...you cannot close the door with the gas cap in the little holder that's built into the door, <s>nor can you close it if the cap is just hanging there (it's attached by a thread of plastic.) You can only close the door when the cap is inserted into the filler hole.</s> [edit to correct. There is no plastic tether, you CAN just lay the cap in there) So the only way I could have done it is for the thing to vibrate and completely unscrew, or if I shoved the cap in the recess and slammed the door closed behind it. And there's still the 10 day delay for the CEL to come on. Hmmmm..... It DOES give one pause.

I posted elsewhere that I went to Advance Auto today. It was throwing 3 codes, all related to gas cap issues (P0442/P0455/P0456.) So that's a relief. The funny thing is they told me they were not allowed to clear the codes. And they could not tell me what the codes meant...told me to go home and look them up on the web. Gotta think it's a real or anticipated liability issue. Interesting, huh?
 
Last edited:
Hey hey HEY!!!! Let's not get smart. ;) And I hadn't thought of that...I DO have bear on the property, as well as very aggressive raccoon. They fear nothing.

I agree that none of it matters now, but your comment got me thinking. I just went outside and checked (even though I got bear hanging around and it's dark)...you cannot close the door with the gas cap in the little holder that's built into the door, nor can you close it if the cap is just hanging there (it's attached by a thread of plastic.) You can only close the door when the cap is inserted into the filler hole. So the only way I could have done it is for the thing to vibrate and completely unscrew, or if I shoved the cap in the recess and slammed the door closed behind it. And there's still the 10 day delay for the CEL to come on. Hmmmm..... It DOES give one pause.

I posted elsewhere that I went to Advance Auto today. It was throwing 3 codes, all related to gas cap issues (P0442/P0455/P0456.) So that's a relief. The funny thing is they told me they were not allowed to clear the codes. And they could not tell me what the codes meant...told me to go home and look them up on the web. Gotta think it's a real or anticipated liability issue. Interesting, huh?

Bear and racoons are freaking smart, too. But their claws are certainly harder than famous Mazda paint!
I didn't catch that you had found the codes.
But I did catch their refusal to help, and I agree with your assessment.
 
Back