I went in for the G30 recall this past Monday and got the latest AV update installed as well. I haven't had the truck give me a sniff of trouble in 15000 miles and then on Tuesday.. DING!.. check engine light comes on. I did the key trick and p0128 comes up. According to what I've found out, this code relates to "Cooling System Error / Thermostat Rationality". I'm thinking that the thermostat may have stuck in the open position that day when I started it, not allowing the engine to warm up to operating temperatures quickly enough and triggering the fault code.

The MIL light's been on all week so I made a service appointment to get it looked at next weekend. Then tonight, I go to start 'er up and the MIL light is gone. What do you all think? Should I keep my appointment and have it checked out, or does the fact that the MIL light is gone mean that there is no longer an issue? There haven't been any drivability issues experienced whatsoever. No loss in performance.

 

lots of times, your service department will not investigate a code unless it is active.

 

I took it my local mechanic(CANNOT STAND MY ***********) and had them clear it off 3,200 miles ago (about 3 weeks ago) and it has not come back

 

that mil lite goes out after ten starts without problems, if it is gone now, I think you should be ok, if it comes back I would definately drive right over so they can get a look at it when it is active.

 

If the MIL light is out you should be OK as far as driveability. However, if it isn't too big of a burden to take your truck in to the dealer, then I strongly suggest you do it. They can read stored codes even if the MIL light is out, and they can fix your issue if the MIL was valid and indicated a real issue. If nothing else, the MIL will be clearly documented in case a bigger issues arises down the road someday.

 

very good point mtnTrucker, always a good idea to take it in so that it is a documented problem

 

I too think it's a problem with the thermostat, going in for the same code tomorrow.

 

Very true. U should be ok, probably stat sticking.

But its about 5 restarts., not 10

 

my check engine light came on within a week of getting the G30. dealer couldnt get me in right away and told me to just drive it if nothing feels wrong. I drove it for a few days and the light turned itself off. the overhead computer said the system was ok the whole time the light was on...

 

That's exactly where I'm at right now as well. I've decided to keep my service appointment and take it in on Saturday. As has been pointed out, it would be a wise thing to at least have the techs look at it and have the issue documented on the vehicle's record for future reference. The fact that it happened the day after the G30 is a bit suspicious to me since I had zero problems with it previously. This is really the first winter that these trucks have faced, so no doubt there is still a lot to be learned by everyone about them.

 

I've been in 5 times for p0128, if the code isn't active all they do is clear it and refuse to try and diagnose the problem. anyone have theirs diagnosed?

can't go more than a week without the MIL, 2300 miles.

 

That depends on the dealer and how edgeumacated they are. Should be some diagnostic procedure to follow.