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 2006 Hummer H3 owners, lightly cleaned up (personal details are redacted by NHTSA).
The contact owns a 2006 Hummer H3. The contact stated that the frame was rusted on the driver's side. The check engine warning light was illuminated. The contact looked underneath the vehicle and was able to see through the subframe. The contact also noticed cracks in sub frame. The contact was concerned about driving the vehicle. The vehicle was taken to an independent mechanic who determined there was an issue with the temperature sensor. While receiving an oil change, it was determined that the subframe was rusted. The local dealer was not contacted. The vehicle was not diagnosed or repaired. The manufacturer was contacted and confirmed that there was no recall coverage for the failure. The failure mileage was approximately 130,000.
On the electrical, I refer to my air conditioning and heater. When I have my air selection to coldest and I drop 1 click for it to be less cool, my heater turns on and at times it smells like something burning. I have to turn it off . On the engine, after I hit 90,000 miles, I have to fill up my engine oil every 2-3 weeks because my vehicle is burning it quick or something. It doesn't leak oil at all. The oil just seems like it's burning somewhere and I ha e to be waisting money to buy oil $30 to $60 a month. Please help. Thank you!
Engine has very bad rough idle after multiple attempts to repair will get a misfire code often that goes on and comes off engine has rough idle to the point where truck shuts off completely while waiting at traffic light. My safety is at risk as this could happen during driving causing a wreck or during a light change when the emergency vehicles need me to move over and my truck don't run. Vehicle was inspected by multiple mechanic and still has issues. Check engine light comes on at time of motor failure or when rough idle.
Was heading home from work and the 2006 Hummer H3 shut off while traveling in the middle of traffic was able to cruise in Nuetral until I could stop to start car again started car and yet again I receive a cylinder misfire code which has been repaired on multiple attempts still no success. I am going to end up either crashing or an emergency vehichle will be trying to get by and I can't move because the motor shut down.
Approximately at 150,000 miles, while making a delivery at the county disposal facility, while moving slowly and parking at each station, the engine started cutting off and idling very poorly, slightly knocking. I made it home checked the oil' which read low, so I changed the oil, over 5 quarts removed, it only requires 6 qts max, and I replaced it with 5 quarts of full synthetic, with bg cleaners. Initially it started, idled, and ran better but after 30 minutes the engine knocks resumed. The next day I took it to my mechanic, he assessed and diagnosed it, concluding that the engine was bad and needed replacing. I had it that confirmed with another mechanic. Went on the Hummer forum blogs and read many similar complaints about the engine and pistons warping or dying between 75K-150K. …
I have owned my 2006 Hummer H3 for the past 8 years and about 5 months ago it began not wanting to start. Not wanting to start no matter what I do and then starting like nothing was ever wrong after 10 minutes. I'm tired of this happening! My H3 just turned 50K miles and I live in florida where the weather is warm... This is definitely a safety issue. As a retired florida police officer I know this to be true... This is a safety issue! You should be able to get inside your vehicle and start it up and leave at your convenience and not when your vehicle decides to... There are so many complaints about this same problem with Hummer H3's I don't understand how there hasn't been a recall on this issue... Go to cargurus.com and read some for yourselves... Having to worry about my wife being stuck somewhere alone because the vehicle will not start is extremely frustrating... …
GM has a security system called passlock that over time seems to fail and trips a "failure" and flashes a key symbol on the dash and disables starting your vehicle until it resets 10 minutes later. This occurs to my wife almsot 50% of the time she tries to start her vehicle. So far GM has come forward with a fix yet I've seen posts on Hummer forumns from hundreds of owners. This has many safety concerns as well as just being a general annoyance: 1) in las vegas we routinely see tempatures over 110f. If the system trips and you have to wait 10 minutes in that heat it can be deadly 2) missing appontments or being late to work because you vehicle intentionally is disabling itself it unacceptable 3) groceries cold/frozen stuck in the heat for 10 minutes waiting for a reset get ruined 4) my wife when alone is stuck waiting outside the vehicle in the heat or locking herself inside waiting for …
More and more frequently when the ignition key is turned to start the engine, the security system activates and disables the engine and prevents it from starting for 10 minutes. There is no possible override so regardless of where you are (on the freeway, on a rr crossing, at a traffic light, or wherever, the engine will spin but will not crank. You are put in the situation of having to physically push the vehicle out of danger or let it sit until the security system resets to attempt to start it. This has also occurred on my 2005 Chevy colrado pickup which is equipped with an identical drive train as my H3 Hummer. This has happened multiple times, more than 25.
Tl* the contact owns a 2006 Hummer H3. While driving 70 MPH, the vehicle independently decelerated to 30 MPH. The stability tracking system, check engine, and a third indicator all illuminated. The failure recurred multiple times. The vehicle was taken to a dealer where it was diagnosed that the wires over the engine failed and needed to be replaced. The vehicle was not repaired. The manufacturer was not made aware of the issue. The vehicle was included in NHTSA campaign number: 15V421000 (visibility). The approximate failure mileage was 50,000.
Tl* the contact owns a 2006 Hummer H3. The contact stated that the vehicle failed to start intermittently. All the warning indicators illuminated on the instrument panel. The vehicle was taken to Cadillac of naperville (located at 1507 ogden ave, naperville, il 60540, [phone]) where diagnostic testing was completed, but a failure code could not be found. The vehicle was not repaired. The manufacturer was notified and did not assist. The approximate failure mileage was 100,000. Consumer stated anti-theft device was malfunctioning.
Engine complaints in other H3 years
Frequently asked questions
How common are engine problems on the 2006 Hummer H3?
NHTSA has 87 complaints about the engine & cooling of the 2006 Hummer H3, 24% of the model year's 362 complaints. The component named most often is engine (6 mentions).
Is there a recall for 2006 Hummer H3 engine problems?
No. NHTSA lists no engine & cooling recall for the 2006 Hummer H3, though it has 4 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 2006 Hummer H3 engine problems start?
Half of the complaints with a recorded mileage happened before about 70,000 miles, and 13% before 25,000 miles.
Is it dangerous?
Owners linked 0 crashes, 1 fire 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.