NHTSA — Engine Problems

2007 Hummer H3 (Page 2 of 2)


hardly worth mentioning
Crashes / Fires:
0 / 1
Injuries / Deaths:
0 / 0
Average Mileage:
73,254 miles

About These NHTSA Complaints:

This data is from the NHTSA — the US gov't agency tasked with vehicle safety. Complaints are spread across multiple & redundant categories, & are not organized by problem.

So how do you find out what problems are occurring? For this NHTSA complaint data, the only way is to read through the comments below. Any duplicates or errors? It's not us.

2007 Hummer H3 engine problems

engine problem

Find something helpful? Spread the word.
Get notified about new defects, investigations, recalls & lawsuits for the 2007 Hummer H3:

Unsubscribe any time. We don't sell/share your email.

2007 Hummer H3 Owner Comments (Page 2 of 2)

« Read the previous 20 complaints

problem #9

Aug 022010


  • 44,000 miles


44,000 miles check engine light came on. Took to dealer I had a cylinder 5 misfire code P300 couple thousand miles later my truck was still showing multiple misfires. I had to replace the radiator because it was leaking and thermostat at 46,000, April 2011 at 65,000miles my transmission went out completely and had to be replaced July 2012 air stop working took to dealer they said I had to replace the fan blower motor resistor. Researched and founded this was a known problem for Hummer the motor gets to hot and melt causing the fan blower to go out. Several months later check engine light came on several more times took to the dealer said they couldn't find problem and cleared code my check engine light came on again so I took to auto zone diagnostic showed cylinder 5 coil multiple misfire so I had spark plugs changed alone with all five ignition coils. Couple months later check engine light came on again took it to dealer diagnostic test reveal code po 300 again and couple other codes dealer said my truck had an emission leak. Multiple misfire, cylinder 5 and a small crack in the head. I didn't understand how that magically happen. I paid the dealer to fix this on March 2014. A week later check engine light came on again. Took to dealer diagnostic showed emission leak apparently they didn't fix it the first time. Week later check engine light came on again took to dealer and diagnostic test reveal torque converter clutch solenoid.dealer said I need transmission replaced. I'm confused at this point the dealer put a newtransmission 3 years prior.my truck has never been over the road. I only drive locally. Now at 103,000 miles the dealer is saying I need another transmission. Something is not right here. After researching I've found thousand of Hummer owners experiencing the same problems I've experienced. Something needs to be done to protect consumers.

- Arlington, TX, USA

problem #8

Jan 262010

H3 5-cyl

  • 66,000 miles
I own a 2007 Hummer H3 with 66000 miles on it. It has been diagnosed as having a bad head due to the use of soft metals for the cylinder sleeve. Due to this, there is sudden reduced power. The cost of this fix is about $4500. My truck began with a check engine light on (autozone) said it was a misfire on cylinder #5. I went to the local dealer and asked them to look at the truck. They diagnosed it as a #5 cylinder having the compression leak of 90%. in looking on the internet (at Hummer forums), I observed that quite a few Hummer H3 owners were writing in about their experience with misfires and bad heads, at about the same mileage. I think this needs to be looked into and that GM should be ordered to do a recall. This is the same problem they had with the 3.5L engines they used in their pre-2007 Hummer H3 and Colorado. I am going to write my congress rep and ask that with the problems that GM is having right now, that this also be moved forward and that they order an investigation. Any other Hummer H3 owners with the same problems should do the same thing.

- West Bend, WI, USA

problem #7

Feb 022014

H3 5-cyl

  • 77,540 miles
Smelled radiator fluent when I parked into the drive way, popped the hood and saw that the liquid splashed all over the engine and parts as well as on top of the plastic fan cover, which seemed odd. Couldn't find the leak in the hose. Looked at the Hummer forum that I'm a member of and lord behold there was a big topic of radiators cracking and breaking in the same places with the 2007 models. No recall has been issued, so no recall has been submitted. But it's a well known defective radiator problem that GM knows about but won't recall. So they decided to make a new radiator that fixes the problem for the 2007 Hummer. The problem is the middle pin that holds the radiator rubs the neck and starts a cracked under the styrofoam, thus the right drivers side cracks in the same spot as well on the plastic side. Hundreds of H3 owners had this happen to them and post pics and what not, but still no recall. This problem is ongoing and nothing is being done. I have spoke to the Hummer customer service and they contacted the local GM and they scheduled my scheduled date to take my H3 in Feb 17 2014, @ 8 am at the local GM dealership and hopefully they will fix this issue and not charged me to fix due to the fact that they know the problem and have done nothing to fix it. But it's been know that they will not fix the radiator and they say it's due to climate which is false because every H3 owner has it break in the same place, and have submitted countless tickets.

- San Antonio, TX, USA

problem #6

Jun 112012


  • 65,000 miles


The contact owns a 2007 Hummer H3. The contact stated that the vehicle lost acceleration power. The contact took the vehicle to the dealer where it was determined that the valve seals in the second and fifth cylinder heads had failed. The dealer stated that the fifth cylinder head was the most dominant and caused the majority of the failure. The contact stated that both cylinder heads had a 70 percent leak. The failure was reported to the manufacturer. The VIN was not available. The failure mileage was 65,000 and the current mileage was 80,000.

- Roseville, CA, USA

problem #5

Apr 202013

H3 5-cyl

  • 160,000 miles
The contact owns a 2007 Hummer H3. The contact stated that while driving 50 mph, exhaust fumes filled the vehicle. The vehicle was taken to the dealer for diagnosis where it was advised to the contact that the manifold gasket needed to be replaced. The vehicle was repaired. The manufacturer was notified of the failure. The approximated failure mileage was 160,000.

- Jackson , WA, USA

problem #4

Apr 102013

H3 5-cyl

  • 47,400 miles
Exhaust manifold bolts are breaking off the block!.

- Albuquerque, NM, USA

problem #3

Aug 222012

H3 5-cyl

  • 67,000 miles


The radiator developed a stress crack and subsequently failed. Dealer advises this is a common problem for this make and model and they stock repair part accordingly. Dealer advised to report incident and enough reports may prompt special service repair or recall.

- Mars, PA, USA

problem #2

Jul 202012

H3 5-cyl

  • 53,600 miles
I am the original owner of a 2007 General Motors Hummer H3. The auto has been well maintained and professionally serviced by a GM dealership. The vehicle has 53,600 miles and is in perfect mechanical condition except this recent issue with passlock security which has rendered the vehicle unreliable and a personal and public safety hazard. The vehicle is less than 30 days out of warranty and dealer will not repair under warranty. In recent weeks, the passlock security light began randomly illuminating while driving. This light could extinguish on next start or stay illuminated through several starts. Two weeks ago while returning from a trip later at night, the vehicle was disabled and failed to start in an airport parking lot. The passlock light continually flashed and the engine cranked, but without starting. A tow truck was called, but by the time it arrived, an attempt to start the vehicle was successful and the light was extinguished. This has happened at least twice since in less inconvenient and less dangerous areas. The vehicle is unreliable and unsafe. I cannot trust it to allow my wife to drive it for fear if her being marooned in a dangerous situation. The dealer has indicated it might be several hundred dollars to repair this problem and was well aware that it was a widespread problem with GM autos. There are hundreds of similar complaints on the internet and yet there is no response or attempt to remedy this situation by the manufacturer. I am a senior citizen and need to rely on my vehicle, but cannot rely on a vehicle whose security system can disable the vehicle at any random time. As my representative, I request the NHTSA address this with the manufacturer and remedy this safety concern. [xxx] information redacted pursuant to the Freedom Of Information Act (FOIA), 5 U.S.C. 552(B)(6).

- Creedmoor, NC, USA

problem #1

Aug 152011


  • 65,370 miles
The contact owns a 2007 Hummer H3. The contact was traveling 40 mph when white steam emitted from the engine. The vehicle was taken to a private mechanic. The mechanic confirmed that the radiator seal was cracked. The manufacturer was contacted. The vehicle was repaired. The failure mileage was 65,370 and the current mileage was 77,000.

- Newington, CT, USA

Not what you are looking for?