 2004 Infiniti QX56; photo by Paul Williams. Click image to enlarge |
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Introduced in 2004, the QX56 was the Infiniti’s first full-size truck, added to the lineup as a replacement for the QX4, a much smaller vehicle based on the second-generation Nissan Pathfinder platform.
The QX56 was based directly on the Nissan Armada, which in turn shared most of its dirty bits with the Nissan Titan full-size pickup. As such, the QX56 was powered by the same 5.6-litre V8 (315 hp/390 lb-ft) found in those two vehicles, backed up by a five-speed automatic transmission and standard four-wheel drive with low-range gearing. Note that U.S. buyers got the option of a rear-wheel drive model.
The engine’s output rose nominally in 2007, to 320 hp and 393 lb-ft of torque. In 2008, the QX got the expected interior and exterior styling update as well as some new standard features, like 20-inch wheels to replace the old 18s, and a heated steering wheel. The ’08 model also got upgraded brake rotors intended to address wear problems in previous model years; more on that later.
 2004 Infiniti QX56; photo by Paul Williams. Click image to enlarge |
Official fuel consumption numbers for the 2004 model were 18.1/12.1 L/100 km (city/highway); by 2009, those figures had improved to 17.3/11.8 L/100 km.
Consumer Reports only has data on a few model years for the QX56 and gives it an average used vehicle reliability rating based on what information it has. The very similar and more popular Nissan Armada gets below-average marks for most model years, however, indicating that there are more than an average number of trouble spots to be aware of.
Infiniti upgraded the brake rotors on the QX56 in either 2007 or 2008, depending on who you ask in response to premature wear and frequent reports of brake pedal pulsations and squealing noises in early models. It seems to have helped: Consumer Reports data on the QX in the “brakes” category shows an improvement between 2006 and 2008. What makes me curious, though, is that the Armada’s brakes get a failing grade all the way through, from 2004 to 2008, so either the better binders were limited to the upscale Infiniti version, or the fix wasn’t that effective.
  2004 Infiniti QX56 (top); 2008 Infiniti QX56. Click image to enlarge |
There’s a common problem with the “variable blower control module,” an electronic piece that makes the automatic climate control work. One of the symptoms is a fan that will only work on high; the fix is to replace the module, which isn’t too expensive and is apparently quite simple to replace.
The QX56 stereo’s Music Box music storage is a source of frustration for many owners.
Consumer Reports notes tailgate troubles in its “body hardware” category. Water is known to leak into the tailgate and cause corrosion or a short circuit in the release switch, which leads to some weird behaviour. Check this thread at Forums.Nicoclub.com and this one at ClubArmada.com for more info. There’s also this issue, of the power-operated tailgate opening, and then immediately closing itself.
The QX56/Armada is very sensitive to out-of-alignment wheels, according to this thread at ClubArmada.com.
 2008 Infiniti QX56; photo by Jil McIntosh. Click image to enlarge |
The QX56 uses an auto-levelling rear suspension. The system isn’t noted for being particularly trouble-prone in these trucks, but it will be an expensive repair if it does fail out of warranty. If this thread at ClubArmada.com is an indication, the suspension’s control unit and/or relays could be a source of trouble.
A QX56 that cranks but refuses to start, or stalls while the truck is being driven is probably suffering from a bad Intelligent Power Distribution Module (IPDM).
