Cold weather No Start
 

H3 wont start when weather below 45 degrees. New battery ,new terminals, new computer, new MAP sensor, cleaned throttle body. When taken to shop its so warm in shop it starts up and doesnt throw any codes. Drove home friday, wake up saturday it cranks but wont start. When on On position the locked car symbol stays solod on dash and doesn't blink. Would it be an ignition switch, ignition module problem or a thermostat problem due to cold temp? Why would cold temps effect ignition switch? Please help before I go bankrupt on this thing.

Hook up your H3 to a battery charger and try doing a passlock reset. Sounds like something is contracting in the cold causing a disconnect. That's all I got other taking the H3 to your mechanic and it gets diagnosed outside in the cold.

I see you indicated new battery terminals. Does that mean new aftermarket or that you simply replaced the existing OEM terminals with another OEM set of terminals?

i love seeing 144000 when im at 72000!!

Aftermarket, the terminals that were on it were hot trash, would never replace with the same terminals.

Mechanic says bad camshaft sensor, intake manifold gasket, and O2 sensors were the culprits. Quoted me $942 to fix all. Do these sound like why my H3 wouldn't start when cold out?

I'm no expert, but from what I've read, the Passlock security system often fails in cold weather. I've read multiple reports of similar symptoms, might want to do a search for that.

I think your mechanic is looking for this month's car payment.

Chance of you needing an Intake Manifold gasket are super slim. It is a known issue with the I5s (due to inherent vibrations) that the intake manifold bolts can become loose and create a leak, tighten them down and drive on.

See this: https://www.hummerforums.com/forum/h...what-do-33916/

Find a new mechanic! Your mechanic obviously did not check the manifold bolts! It appears your mechanic is slow and needs money, or does not have a clue as to how to properly diagnose/repair, just throw some parts at it.
Start by re-torquing the manifold bolts, correcting the lean condition, which would then eliminate the need for O2 sensor replacement. GL