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The Hummer is a brand of pickup and SUV models that has become iconic over the past several decades. After debuting in the early 1990s, Hummer quickly achieved notoriety due to its large size and impressive road presence. In 2010, the Hummer was discontinued due to the combination of the vehicle’s high gas mileage and the nation’s rising gasoline prices. These days, the Hummer is being revived as an EV, but many drivers still choose used models when they want to make a statement. However, while Hummers always catch the eye, owning one of these behemoths also has some significant drawbacks. Here are the brand’s most common maintenance issues. 

1. Worn valve seats

Three primary problems plague the Hummer. The most notable of these is the issue of worn valve seats. RepairPal breaks down the numerous complaints filed by Hummer owners involving worn valve seats. About 127 complaints of worn valve seats exist on the website, with the reports noting that the worn valve seats caused engine misfires. The website reports that the problem typically surfaced around 93,430 miles on average, primarily affecting Hummer models from the 2006, 2007, and 2008 model years, including the popular Hummer H3.

Worn valve seats often triggered the check engine light to illuminate. Fixing the problem usually necessitated replacing the cylinder head. Still, by the time the issue was diagnosed, owners could expect to have shelled out anywhere between $80 and $150 for diagnosis and testing.

2. HVAC and air delivery failure

A pair of Hummer H2 large SUV models at the Weil Hummer dealership in Libertyville, Illinois
Hummer H2 models | Scott Olson via Getty Images

Second to worn valve seats is the problem with Hummer HVAC and air delivery failure. RepairPal highlights that well over 100 drivers reported this problem, which involved improper HVAC temperature and air delivery problems that typically started around a mileage of 118,227. The issue was particularly prevalent in Hummer H2s from the 2003-2009 model years.

Consumer comments call out effects such as a lack of cool air when the AC is turned on, air blowing out only through defrost vents, and hot air blowing in rather than cool air. Diagnosis and repair of this issue could also be complicated, with RepairPal’s comments revealing that users had to address the problem by replacing the door mode activator. This frequently coincided with the replacement of the Hummer’s battery.

The diagnosis alone cost around $100, as reported by RepairPal. The total cost of the repair, however, tended closer to $150-$200 or more, depending on the repair shop and whether drivers chose to have the problem fixed at a dealership.

3. Check engine light and gas cap issues

Finally, Hummers have been notoriously plagued by maintenance issues involving the check engine light and gas cap. About 68 people reported this specific problem on RepairPal, noting that it’s prevalent in the Hummer H3 for the 2006-2010 model years. It surfaced at an average mileage of 90,530. This could be the most quick-to-diagnose problem, with a loose or worn gas cap causing the check engine light to illuminate.

Although the problem has a deceptively simple root, it caused several drivers considerable stress, with RepairPal comments from Hummer owners slamming the defect as especially annoying. Furthermore, several drivers noted that the problem kept happening even after purchasing a replacement gas cap. While it wasn’t an expensive part to replace, with owners reporting that they spent about $30-$50 on the repair, it caused some to lose faith in the manufacturer entirely – proving that while the original Hummer nameplate is iconic, it wasn’t without issues.

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