Which parts fail
Components named in complaints (engine, cooling system, oil leaks, timing chain, exhaust).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2007 Hummer H3 owners, lightly cleaned up (personal details are redacted by NHTSA).
The contact owns a 2007 Hummer H3. The contact stated while driving at 50 mph, the vehicle started to overheat and stalled. The contact stated the temperature and the check engine warning light were illuminated. The vehicle was then towed to a local dealer where it has yet to be diagnosed due to the battery needing to be replaced. The vehicle was not repaired. The contact had the vehicle serviced under NHTSA campaign number: 15V421000 (Visibility) prior to experiencing the failure. The manufacturer had not been informed of the failure. The failure mileage was approximately 160,000.
Everything from: electrical, air condition, stabilitrack system, which cost me over $600.00 still not working properly. Leakingsun roof censors, I was made to pay for that still dont work. I paid over $8,000.00, or more. When ever I brought my vechicle in, I was forced to for something else, my vechile only had about 22,000.00 miles. I was taking it to GMC/vera Cadillac 300 pembroke pines, fl 33025, ph:[phone], service manager mr.gustavo, edwin montoya. I have over 50 pages documents about fake repairs, my vechicle is wrost off now than before. It also has safty issues, mold/medw, ac overheating, airbag not working, etc. I am afraid for my safty.
On 3/13/2020 my wife was driving our 2007 Hummer H3 when the engine compartment and dash area caught on fire. The blower motor connector module had been replaced recently as part of a safety recall. The vehicle was in motion and she had just made a left turn. Although the part had been replaced, I still believe that this recall issue was the cause of said fire. The fire department called it an electrical issue. There was no warning at all. This was traumatic for my wife she had to jump out of the vehicle and had a miscarriage.
Tl* the contact owns a 2007 Hummer H3. While the vehicle was parked, the key became stuck in the ignition and could not be removed. The vehicle was towed to a dealer where it was diagnosed that the ignition cylinder failed and needed to be replaced. The dealer made many attempts to repair the vehicle, but the remedy failed. In addition, various electrical functions failed and a burning odor was noticed. The manufacturer was notified of the failure. The failure mileage was 7,000.
Sir/ma'am, I am writing to complain about the 2007 Hummer H3 security system not allowing the vehicle to start under certain conditions. I maintain my vehicle to high standards and over the last 8 months have had issues starting my Hummer. When the Hummer does not start, you must wait 10-15 minutes to even attempt to restart. The vehicle will turn over, but no fuel is sent to the engine to start. If it doesn't start again, you must wait another 10-15 minutes. The latter has happened to me 5 or 6 times in just the last 2 months. There have been numerous complaints to GM about this exact issue, and has fallen on deaf ears. …
While driving at 65 miles per hour the vehicle dash lit up all service lights the vehicle went into reduced power mode not allowing the vehicle to exceed 40 MPH and ABS sensors came on staying traction fail, ABS fail, began to stutter and stall. Took to shop. Vehicle running codes for spark plugs, replaced spark plugs. Few weeks later did it again, this time saying throttle body. Replaced it, a month later did it again, each time in major traffic having to pull off roadway to avoid an accident. This time says misfiring, throttle body, ABS,TPMS, thermostat, etc. Take it to have compression test run and system says cylinder failure. Do research on issue and find that there are hundreds of complaints about this online having caused accidents and thousand of dollars spent by consumers after having accidents but no known fatality so GM will no recall or honor the issue repairs. …
The radiator has a crack in it which is a very common issue...needs to be recalled. My H3 was idling rough and would shut off. Had to replace throttle body and solenoid. The anti-theft acts up and the H3 won't start have to wait 10 minutes. The ac blower and connector burnt paid for it to get fixed then the recall comes out 7 days later....still haven't been refunded for that. I have all the issues on my 2007 H3 that should all be recalled and fixed at GM expense. Sunroof drains get clogged all the time and have water leak onto the floor which makes the ABS light trigger on and off. Issue after issue which GM doesn't take any responsibility for. It looks like it's time to sell the Hummer H3!!
Tl* the contact owns a 2007 Hummer H3. While driving various speeds and approaching a stop, the vehicle overheated. The check engine warning indicator illuminated. The contact coasted to the side of the road, powered off the vehicle, and waited for a few minutes to restart it and resume driving. The vehicle was taken to stingray Chevrolet bartow (1475 w main st, bartow, fl 33830, [phone]) where it was diagnosed that the speed sensor failed and needed to be replaced. The vehicle was not repaired. The vehicle was later taken to an independent mechanic where the thermostat was replaced; however, the failure recurred. The manufacturer was not contacted. The approximate failure mileage was 136,000.
Vehicle would not start called dealership where car was purchased - replaced ignition switch after diagnosis. Since then have had repeated episodes of vehicle ignition/electrical just shutting completely down on different occasions. I could be sitting or approaching a stop light vehicle shuts down upon taking off or idling down, vehicle also shuts down when making turns as well. It occurs so infrequently and has no pattern but it is indeed a safety concern because I have to put on the flashers and take time to restart the engine all before someone runs into me.
About 2 years after I bougth car from dealer ,the car cranks but wont start you have to wait 20 minutes and it starts today it left me stranded over 60 miles away ,it has being doing this every few months ,I saw a forum with hundreds of people having same problem and dealer says it doesent find anything that's what I was told two times at dealer ,from the forum it seems to be a faulty passlock security problem or a faulty egnition switch on several years of hummers ,GM needs to recall this because is causing lots of expenses to a lot of people including me
Engine complaints in other H3 years
Frequently asked questions
How common are engine problems on the 2007 Hummer H3?
NHTSA has 56 complaints about the engine & cooling of the 2007 Hummer H3, 24% of the model year's 238 complaints. The component named most often is cooling system (1 mentions).
Is there a recall for 2007 Hummer H3 engine problems?
No. NHTSA lists no engine & cooling recall for the 2007 Hummer H3, though it has 2 recalls for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 2007 Hummer H3 engine problems start?
Half of the complaints with a recorded mileage happened before about 74,000 miles, and 8% before 25,000 miles.
Is it dangerous?
Owners linked 1 crash, 3 fires and 0 injuries to engine & cooling problems on this model year. If you notice symptoms, have the car checked before driving further.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.