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Gm Tech (Cam)
Gm Tech (Cam), GMC Mechanic
Category: GMC
Satisfied Customers: 1672
Experience:  GM Grand Master Technician 2007. 14 year experience.
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2004 Yukon check engine light comes on intermittently. I

Customer Question

2004 Yukon check engine light comes on intermittently. I warm weather, never comes on, in colder weather, it will come on for a day or two and go off for a while, then back on.... any idea why this might happen?
Submitted: 6 months ago.
Category: GMC
Expert:  Jared D replied 6 months ago.

Hi,

It really depends on what system is triggering the code, but usually the only thing that can be affected by weather like that would be either a temperature sensor or a fuel pressure sensor (fuel expands more when it's warm). In my opinion the most likely cause is a stuck open thermostat which only triggers the code when cold because the engine doesn't think it's heating up to operating temperature quickly enough (caused by a stuck open thermostat).

Is there any way you could get the vehicle scanned for trouble codes?

Customer: replied 6 months ago.
Yeah, did not think of that, will go get that checked out.I also have a slow oil leak - looks like rear main seal - do any of those oil stop leak treatments work? Will they harm the engine?
Expert:  Jared D replied 6 months ago.

I like the Lucas stop leak product. It seems to do a good job without gumming anything up.

Customer: replied 6 months ago.
Thanks, ***** ***** try that
Expert:  Jared D replied 6 months ago.

Please let me know if you need additional info.