Any one else having this check engine light?

[H3 Alaska]

All 3 (mine/wife/brother in law) of ours have had a check engine light in the last 2 weeks.

Wife: P300 engine misfire
Mine: P302 engine misfire
Brother in law: who knows (whole other story)

Mine only happens after the "low fuel" indicator comes on. ??????????
Once I fill up the tank, it goes off.
The wifes goes off and on at random.
All have less than 10K, but more than 8K miles.

Wife's is going in for cylinder head replacement today.

f5stop? Any suggestions?

Regards,
Dan

[wpage]

Mine has gone on as I have experimented with air intake mods.

[f5fstop]

Originally Posted by H3 Alaska

All 3 (mine/wife/brother in law) of ours have had a check engine light in the last 2 weeks.

Wife: P300 engine misfire
Mine: P302 engine misfire
Brother in law: who knows (whole other story)

Mine only happens after the "low fuel" indicator comes on. ??????????
Once I fill up the tank, it goes off.
The wifes goes off and on at random.
All have less than 10K, but more than 8K miles.

Wife's is going in for cylinder head replacement today.

f5stop? Any suggestions?

Regards,
Dan

If there is a rough or rougher than usual idle with those codes, a new cylinder head is coming your way. However, if no idle and the light only comes on when the tank is real low, I might say it could be a fuel pump. Lack of fuel is causing a misfire, setting the code. Not a usual occurrence, but it could happen.
When the low fuel is on, what is your fill up in gallons? It could be your low fuel light is coming on too late, and you are about out of fuel and the pump is starving a bit.

[H3 Alaska]

Last night when it happened I only put in $15 because I was late for dinner at my sons, and of course everyone was waiting on me.

I will look back at some recent fuel receipts and post back.

The wife's did have a rough idle, but mine does not.

[Hummergyrl]

There is a known issue/bulletin out on this issue for P0300 thru P0305 Emissions misfire DTC. You will get a Check Engine Light and may or may not experience rough idling. *Some* VINS under 287591 have these parts that were machined wrong or something and need to be replaced. The new parts contain harder intake valve seats to prevent intake valve wear and leakage.

This happened to me last week. My H3 (7,500 miles) had been idling a little rough for a couple weeks and then got the Check Engine Light. Onstar diagnosed the DTC and said to go directly to the dealer. The dealer replaced some intake valves and the cylinder head. Runs great so far. Sad to see my brand new H3 with the motor torn apart though.

Nothing to do with gas folks, get it fixed asap!

[smh3]

Took mine to about 12,500'. All kinds of things came on. Long story short it was a Mass airflow sensor.

[Hummergyrl]

H3 Alaska did your wife's get the cylinder head replacement? Did it resolve the issue?

Mine is still running good...

[f5fstop]

Yes, did you get a new cylinder head?
Just a note to everyone, you can drive upwards of 5K miles with this problem with the cylinder head. All that is happening is one of the intake valve guides (usually in cylinder number 1, but can be any cylinder) has elongated, and causing a misfire. The misfire is picked up by the knock sensor and thus the 300+ code(s) is set.
The idle will get worse, but the engine will continue to run, and the only damage being done is to the cylinder head, which has to be replaced anyway.

[H3 Alaska]

Wife's is a done, and seems to be fine.

Mine goes in on Tuesday for a traction control module I've been waiting on, and to have a look regarding the head issue. It has developed a rough idle since last post. No wheel'n for me this weekend.

Will post back here after with exact issues once I pick it up.

Never seen that light. I've run my fuel down to "low fuel light" level with at least 2 gallons left about 5 times.

S.

[Hummergyrl]

Originally Posted by H3 Alaska

Wife's is a done, and seems to be fine.

Mine goes in on Tuesday for a traction control module I've been waiting on, and to have a look regarding the head issue. It has developed a rough idle since last post. No wheel'n for me this weekend.

Will post back here after with exact issues once I pick it up.

Mine idled rough for probably 3 weeks before I got the check engine light with the P0300 code.

[H3 Alaska]

FYI. She's in the shop getting the top end ripped off right now

[Hummergyrl]

Aww, that's about how I felt. Atleast after the boiling stopped. I was pretty mad about it at first, mostly worried that once they started taking everything apart it would never be the same or they'd miss a bolt here or there. The beginning of the end.

Then when it was finished they asked me if the mechanic could take it home overnight to "test drive". I said, "hmmm, take my Hummer home to some seedy neighborhood...uhhh, NO." The Service Manager said, "Oh come on, these mechanics are family men." I said, "Oh, so he will stop and pick up his family in my Hummer and take them to Walmart and buy them all slushies to spill in my seats...NO"

Perhaps I'm no fun.

[H3 Alaska]

Got it back after 7 days (including Sunday), not too happy about the length of time in since the paperwork says 11.3 hours of shop time.

I only drove about 10 miles home and it seems to be fine. It does seem to have a little more "pep" off the line, but it could be just me happy to get my baby back.

These kind of things happen and no one take me wrong on this. I've had several new vehicles other than GM (mostly company trucks), that have had WAY more problems under warranty.

I wouldn't have 2 of these things if I didn't love it.

Time to do some wheel'n and a little fishing this coming weekend out at the cabin.

[macwag]

Yes. My engine check light went on yesterday at 10,300 miles. My brother is a GM mechanic and he said there is a new cylinder head heading my way.

[H3 Alaska]

Just took it back in this morning because it was running rougher than before the new head. Service advisor said it's a "cam shaft sensor".