DTC Code P0300 - Multiple Random Cyliner Misfire - Hummer Forums - Enthusiast Forum for Hummer Owners

Hummer H2 For those who like a little more gleam to their Hummer, the H2 offers a similar rugged look as the H1, but as a lower cost, and with more added features, making it almost a massive luxury SUV.

Thread Tools Search this Thread
Old 07-19-2007, 11:00 PM
Thread Starter
Join Date: Jan 2007
Posts: 42
Default DTC Code P0300 - Multiple Random Cyliner Misfire

Hey Guys,

Well, my H2 has been in the shop now for almost 2 weeks. I won't go in to the details, but it was running very poorly, and I was getting a DTC code of P0300, "random multiple cylinder misfire". I took it in to the dealer to have them re-flash my ECM back to a stock tune (it had been modified), and the dealer fried the ECM computer. They refused to take responsibility for it, so I told them where they could stick it, and had a tow truck hall my H2 out of their shop. (Needless to say, I am not invited back there again)

I got a new ECM from a place called Wester's Garage (www.ecmprogrammer.com) and installed it. Super shop by the way!! The truck runs again, but still doesn't run properly.

It went in to a local shop that I once worked for many years ago, and whom I feel I can trust. They have been working on diagnosing the problem, but are not having much luck. When attached to the scope, monitoring each cylinder, it appears that different cylinders will randomly shut down, and then start working again.

Has anyone experienced a problem similar to this? Any information might lead to an answer, and will be greatly appreciated.


Reply With Quote
Old 07-31-2010, 11:29 PM
Junior Member
Join Date: Jul 2010
Posts: 1
Default DTC code PO 300

did you ever get to the bottom of the the issue? my Modded truck just started to do the same thing?

Reply With Quote

Related Topics
Thread Thread Starter Forum Replies Last Post
P0300 cylinder 2 misfire or not? juicebox123 Hummer H3 2 11-03-2014 10:57 AM
random misfire at idle pakerosny Hummer H2 8 07-02-2013 12:47 AM
random misfire 03 H2 po300 Pdmiller Hummer H2 6 09-15-2012 10:09 PM
Random misfire code P0300? H2 pm1010 Hummer H2 1 09-13-2012 11:11 AM
p0300 random missfire mrigor Hummer H3 4 07-30-2011 01:39 AM

07, 2003, code, codes, cyclinder, cylinder, dtc, h2, h3, hummer, misfire, multiple, p0300, random, reflash

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

All times are GMT -5. The time now is 01:48 PM.