Any one else having this check engine light?

[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