flashing check engine light

[at81]

I have less then 3k miles on my new gladiator. First time this happened was last month. Both times it happened as soon as I backed out of my driveway lasted for about 10-20 seconds and turned off. I've taken it to the dealer but they won't do anything because a code isn't saved. I read it could be a misfire? Is there anything I can do to get the dealer to check more into this if there is no code saved? I'm getting frustrated at this point.

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[WesternJeep401]

A flashing MIL indicates that powertrain has detected an active misfire. In tech-speak, one or more specific cylinders are being detected as performing outside of IM spec; it could be ignition, fuel, engine mechanical, or glitchy data, among others. Might be worth your time to scan it yourself simply to verify what you're being told; a flashing MIL is "top priority", with code(s) stored for that, along with freeze frame(s) (a snapshot of data at time of the event, like a flight recorder).

 

[AmishMike]

Try to isolate what you did. Exactly what you did.
Cold start, what is the outside temp? Did you warm it up at all? Was it hit button and roll? Every little detail could tell you what is happening.
Throw a notepad in and write down what is happening when the light flashes and what happens when it doesn’t. If it is a consistent pattern that makes it happen, then you should be able to duplicate it for the dealer. Or it could be a ‘characteristic’ not an actual problem.

 

[Lunentucker]

There have been two computer updates that may help with this. Do you know if your Gladiator has had them or was eligible? The dealer SHOULD have taken care of it.
How "new"?
What year?
How long have you had it?

 

[at81]

How "new"?
What year?
How long have you had it?

less then 3k miles so new 2023 Mojave i've had it for 3 months

 

[Lunentucker]

My intermittent misfiring issue was abated when the tech swapped the problem coil pack and plug with the adjacent one, but he also flashed the PCM with the Z37 update at the same time.. So it's uncertain if it was just a poor connection that was fixed with the swap or if it was the flash.
Whichever, it's been fine for 5000 miles.

They need the code to stay in before they can read it. Light stays on.
Take it out on the highway and floor it going uphill.

 

[Lunentucker]

less then 3k miles so new 2023 Mojave i've had it for 3 months

You can login on the FCA site and input your VIN to see if there are any TSBs that haven't been done.

 

[Bobchadwickga]

Do you get a solid light after. Mine has done it three times in 9 months, gives me a solid CEL after and then the solid CEL clears after 3 or 4 starts. I have a code reader and read P301, which is intermittent misfire. I took it to the dealer and got the same message you did.

 

[at81]

Do you get a solid light after. Mine has done it three times in 9 months, gives me a solid CEL after and then the solid CEL clears after 3 or 4 starts. I have a code reader and read P301, which is intermittent misfire. I took it to the dealer and got the same message you did.

no solid light after. It just goes away

 

[ShadowsPapa]

You can login on the FCA site and input your VIN to see if there are any TSBs that haven't been done.

True - but then I took mine in and there was one while Jeep's app said no, it's fine.
Apparently there's some time lag at times?

A flashing MIL indicates that powertrain has detected an active misfire.

Yeah, and "not always". I got that when mine was having CANbus communication issues as well. Beep, flash, and it was gone. I used JSCAN to do a deep scan for codes and found a half dozen or so.

On the other hand, mine did the flashing MIL, beep, and even NO MIL at all when it had misfires.
The misfires were VERY specific as to when they would or would not happen.
Even the tech had to duplicate my directions exactly to make it happen. They could not force a misfire in the stall, as written in the ticket, but when they drove it and got it good and warm,. parked it for 30 minutes, then restarted it, it happened. They caught it in the act.
Cold it was fine. Driving it was mostly fine (more misfires than I'd like but not problematic in the grand scheme) It only happened when it was warmed up, then parked, then started again and only at low RPM - idle or off-idle RPM up to around 1200 RPM or so. It always came out of it on its own.

CCDIFF learn process had never taken place so they forced a relearn last November. Then this month they said there was a PCM flash for me. It's not done it since November when they forced the CCDIFF learn.

Since the instructions for the STAR bulletin for my misfire back in November said they were to take care of any other code before proceeding, it appears they have also resolved my CANbus communication issue as I've had no errors since.

Anyway, my misfires cause a MIL sometimes, other times it just flashed and went away. I captured freeze frames for the events as well as logging the codes and other info from those times. Even with no obvious codes, the codes for the misfires did exist with a deeper scan.
Cylinders 2, 4 and 6 - left bank only. 2 was the worst, at times not firing at all for 2 minutes, other times just hundreds of misfires. 4 was behind 2 in numbers of misfires, still horrible though, and 6 was less than 4 but still waaay off normal.

Now, though, I'm dealing with a temp sensor that says it's anywhere from 55 to 101 degrees outside when it's really 0 to 20 degrees out........ ugh.

 

[WesternJeep401]

True - but then I took mine in and there was one while Jeep's app said no, it's fine.
Apparently there's some time lag at times?



Yeah, and "not always". I got that when mine was having CANbus communication issues as well. Beep, flash, and it was gone. I used JSCAN to do a deep scan for codes and found a half dozen or so.

On the other hand, mine did the flashing MIL, beep, and even NO MIL at all when it had misfires.
The misfires were VERY specific as to when they would or would not happen.
Even the tech had to duplicate my directions exactly to make it happen. They could not force a misfire in the stall, as written in the ticket, but when they drove it and got it good and warm,. parked it for 30 minutes, then restarted it, it happened. They caught it in the act.
Cold it was fine. Driving it was mostly fine (more misfires than I'd like but not problematic in the grand scheme) It only happened when it was warmed up, then parked, then started again and only at low RPM - idle or off-idle RPM up to around 1200 RPM or so. It always came out of it on its own.

CCDIFF learn process had never taken place so they forced a relearn last November. Then this month they said there was a PCM flash for me. It's not done it since November when they forced the CCDIFF learn.

Since the instructions for the STAR bulletin for my misfire back in November said they were to take care of any other code before proceeding, it appears they have also resolved my CANbus communication issue as I've had no errors since.

Anyway, my misfires cause a MIL sometimes, other times it just flashed and went away. I captured freeze frames for the events as well as logging the codes and other info from those times. Even with no obvious codes, the codes for the misfires did exist with a deeper scan.
Cylinders 2, 4 and 6 - left bank only. 2 was the worst, at times not firing at all for 2 minutes, other times just hundreds of misfires. 4 was behind 2 in numbers of misfires, still horrible though, and 6 was less than 4 but still waaay off normal.

Now, though, I'm dealing with a temp sensor that says it's anywhere from 55 to 101 degrees outside when it's really 0 to 20 degrees out........ ugh.

" In tech-speak, one or more specific cylinders are being detected as performing outside of IM spec; it could be ignition, fuel, engine mechanical, or glitchy data, among others. "

 

[ShadowsPapa]

" In tech-speak, one or more specific cylinders are being detected as performing outside of IM spec; it could be ignition, fuel, engine mechanical, or glitchy data, among others. "

I was making note that it doesn't have to be related to a misfire.
When mine was NOT misfiring, cold start, it was totally related to missing messages from the shifter.
It wasn't even engine related - not even a little bit, not engine data, not ignition, not mechanical.
You are suggesting a flashing MIL means misfire OR it thinks there is a misfire.

I'm just pointing out that no, not always. All cylinders could be fine and the PCM says life is good, no misfire or engine issues detected.
The flashing light may not even be engine related at all.
So those with a flashing MIL should not jump on the "MISFIRE!" bandwagon.

No misfires here - and it caused flashing MIL -

Not related to engine or misfire as you stated:
>>one or more specific cylinders are being detected as performing outside of IM spec<<
This is all transmission related.

Last October or November, I got a flashing MIL when I first started my truck. I knew it wasn't misfire related. I launched JSCAN and this is what was causing the MIL to flash (which them went away on its own after a few seconds)

The above caused flashing MIL on my 2022.

 

[WesternJeep401]

" or glitchy data". We refer to strings of network U's as "it's trying to launch the missiles!" However, a flashing MIL is nested at high-priority with IM240, and should be addressed quickly, regardless.

 

[sharpsicle]

A flashing MIL indicates that powertrain has detected an active misfire. In tech-speak, one or more specific cylinders are being detected as performing outside of IM spec; it could be ignition, fuel, engine mechanical, or glitchy data, among others. Might be worth your time to scan it yourself simply to verify what you're being told; a flashing MIL is "top priority", with code(s) stored for that, along with freeze frame(s) (a snapshot of data at time of the event, like a flight recorder).

I wouldn't assume it's a misfire-related issue. That's a bit of an assumptive jump. But there's something there and he needs help running it down. Putting the blinders on to say "misfire" is likely going to hurt more than it helps.

The problem is you state it's a "top priority, with code(s) stored for that" but his dealer specifically said there's no stored code to diagnose the issue. That's where he's fallen flat with no idea what to do. There's a decent chance this is something other than your description of being cylinder-fault related.

As others have said, it's really going to come down to finding the pattern and finding out how you can replicate the issue for the dealer.

 

[at81]

thanks for the help everybody! i'll try to pay more attention to what causes it. Since it's right after startup i'm assuming it's only happening with a cold engine but it's right after i switch into drive from reverse so it could also be something with the drivetrain.

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