CEL p300 code

[GR00VY]

2022 gladiator 24,000 miles

I just got back from the dealership. The check engine light came on a couple days back so I scheduled an appointment to get it checked and get my oil changed.

Tech wrote up this about the light, “check for codes. Found p300 and random misfire, while check g for codes found a software update for the pcm to help with the code. Corrected by TSB 18-001-19 flash pcm updates.”

is this p300 a common issue for pcm update or are they just trying to throw a bandaid on the issue?

truck was running fine even with light on.

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[MT1]

What year JT?

P309 would be a misfire on cylinder 9, which is, unlikely, on a V6.

 

[Thunderspud]

P309 would be a misfire on cylinder 9, which is, unlikely, on a V6.

I agree, although I am gonna give the benefit of the doubt to the OP and assume they may have fat-fingered a 9 since it's dangerously close to 0 on most keyboards.

 

[GR00VY]

What year JT?

P309 would be a misfire on cylinder 9, which is, unlikely, on a V6.

2022. I looked up ts 18-001-19. The number in my notes. It has nothing to do with a jeep gladiator. The tsb is for a Pacifica from 2018.

 

[GR00VY]

I agree, although I am gonna give the benefit of the doubt to the OP and assume they may have fat-fingered a 9 since it's dangerously close to 0 on most keyboards.

p300. Sorry for the typo

 

[GR00VY]

I’m worried they just updated the pcm and didn’t actually fix the problem.

 

[ShadowsPapa]

2022. I looked up ts 18-001-19. The number in my notes. It has nothing to do with a jeep gladiator. The tsb is for a Pacifica from 2018.

I'm finding multiple results for that TSB number.

If it was running fine - and the TSB applies to that engine and code - then they did what one would first to absent any other symptoms, etc.

The 19 indicates the TSB was released in 2019, so does seem a bit early for the JT, however, I wonder if the TSB number is incorrect. They can't apply a PCM update for a different vehicle - they are applied to a specific vin so it's not possible to apply a flash for a Pacifica to a Gladiator.

 

[Lost1wing]

Step 1, perform tsb.
Step 2 blame it on bad fuel
Step 3 actually do something about it.

The TSB is a reset on the parameters for a misfire p300 if I remember.

 

[ShadowsPapa]

Step 1, perform tsb.
Step 2 blame it on bad fuel
Step 3 actually do something about it.

The TSB is a reset on the parameters for a misfire p300 if I remember.

If that's the correct one, and may well be, I'm surprised a 2022 going to a dealer for anything didn't get flagged to have it applied. But, maybe it was only "if customer complains".

With no other symptoms - probably resolved.

 

[Hootbro]

I think your tech just got lazy and miss-entered a incorrect TSB number that he was probably already familiar with.

There has been multiple TSB's dropped over the years for the Gladiator reflashing the PCM for misfire issues. May or may not fix anything but it is first step unless you have a hard code setting criteria.

Attached is TSB 18-071-22 for 2022 Gladiators and is probably what got flashed.

 

[ShadowsPapa]

I think your tech just got lazy and miss-entered a incorrect TSB number that he was probably already familiar with.

There has been multiple TSB's dropped over the years for the Gladiator reflashing the PCM for misfire issues. May or may not fix anything but it is first step unless you have a hard code setting criteria.

Attached is TSB 18-071-22 for 2022 Gladiators and is probably what got flashed.

That one is probably one of those that resulted from what my 2022 had - I see CCDIFF mentioned. There was an issue with the PCM where the CCDIFF wasn't learned. Typically it resulted in a hot restart misfire - one you didn't necessarily feel, and may or may not set the MIL

 

[MT1]

p300. Sorry for the typo

No worries, just checking with the P code and the TSB being for a 2018 Pacifica; gotta start with clean data.

They have to start somewhere, and getting your JT on current software is a good start if there are no other facts/symptoms. The bugs listed as fixed in the two TSBs could result in a false check engine light.

It might sound silly, but, you might also check your battery condition. Low voltage could also be a cause for bad data to the PCM, resulting in the CEL. Garbage In means Garbage Out. There are few threads on correctly checking each battery if the overall voltage is low.

One vehicle here throws a CEL for the downstream O2 sensor low voltage if we let it sit too long, and the batt voltage gets low. There is no impact on performance or mileage while lit. The CEL goes away after charging the battery and a couple hundred miles. The batt is 5 years old and due for replacement before winter. ;-)

 

[ShadowsPapa]

The bugs listed as fixed in the two TSBs could result in a false check engine light.

For those lurking or learning or just hanging out -

If you search for CCDIFF, you might find my posts about my weird situations with misfires.
It was a very strange thing - resulting in either misfire detection by the PCM when you felt nothing, also causing the ESS to not work but no MIL, or, a misfire so bad you couldn't drive it, with no MIL set!

I took mine in before there was a TSB for the fix, STAR was looking for vehicles with symptoms like mine and asked the dealers to submit the findings, and to force a CCDIFF relearn if they found certain readings in the CCDIFF data.
It did fix it, and weeks later, a TSB came out addressing the issue. They just did a PCM reflash rather than manually force the relearn. Apparently something in the code caused it to not always learn the crank/cam difference or timing.

It applied to 2022, can't recall if it applied to others.

 

[GR00VY]

No worries, just checking with the P code and the TSB being for a 2018 Pacifica; gotta start with clean data.

They have to start somewhere, and getting your JT on current software is a good start if there are no other facts/symptoms. The bugs listed as fixed in the two TSBs could result in a false check engine light.

It might sound silly, but, you might also check your battery condition. Low voltage could also be a cause for bad data to the PCM, resulting in the CEL. Garbage In means Garbage Out. There are few threads on correctly checking each battery if the overall voltage is low.

One vehicle here throws a CEL for the downstream O2 sensor low voltage if we let it sit too long, and the batt voltage gets low. There is no impact on performance or mileage while lit. The CEL goes away after charging the battery and a couple hundred miles. The batt is 5 years old and due for replacement before winter. ;-)

I’ll check voltage just to be sure. I guess if updating the PCM is a legit fix I will just keep an eye on it.

 

[GR00VY]

Thanks everyone. This has been very insightful.

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