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The Mercedes-Benz G-Class SUV has a reputation for bulletproof reliability. This makes sense, considering the boxy Mercedes “G Wagon” SUV was engineered for military use back in 1979. But even the mighty G Wagon is not without its problems. Here are the most common G-Class issues owners reported to the RepairPal website.

  • Door lock and window switch failure
  • Oil level sensor or crankshaft position sensor failure
  • Brake light switch failures

Door lock, window switch, and door handle failure

Closeup of the grille of a gray Mercedes-Benz G Wagon SUV which has been known to experience engine sensor problems.
Mercedes-Benz G-Class | Lowie Vanhoutte via Unsplash

The G Wagon door lock, door handle, and window regulator problem is exactly what it sounds like. Owners of G Wagon SUVs report that one or all these components fail, leaving a window stuck down or a door that can only be opened from the inside. From owner comments, it seems that these issues aren’t always connected, but instead that all these components are simply prone to occasional failure in early G-Class SUVs.

RepairPal recorded 34 complaints of this problem on G 500s from 2002 through 2008—with an average mileage of 97,028. It also received an additional 15 reports of the same problem from owners of G 55 AMG SUVs from 2003 through 2010—with an average mileage of 89,800.

Even though these problems sound frustrating, none of them threatens the drivetrain’s reliability—a broken window motor won’t leave you stranded. RepairPal estimates the average repair cost will be $110-$139, for each instance of each issue.

Oil level sensor or crankshaft position failure sensors

Black and white photo of a G-Class Wagon Mercedes SUV parked facing away from the camera, a brick wall visible in the background.
Mercedes-Benz G-Class | Endri Killo via Unsplash

Two different G Wagon engine sensors have been known to fail, with very different results. These issues shows up on both regular G-Class SUVs, and the G Wagon tuned by AMG.

The first sensor is something called the crankshaft position sensor. Not to get too technical, but this is essentially a magnetic pick up the engine control module uses to tell exactly where the crankshaft is. Crankshaft position affects processes like ignition and opening the valves, and thus the ECM won’t let the engine run unless the sensor is working. The good news is that this feature can prevent very expensive engine damage, but the bad news is that a simple sensor failure can leave you stranded.

A total of 12 Mercedes-Benz G500 owners reported this issue on SUVs from 2002 through 2008. The sensor failed at 162,500 miles on average but can fail as early as 100,00 miles. In addition, 10 Mercedes-AMG G55 owners reported the exact same problem. Affected AMGs include the 2003 through 2010. This problem strikes the AMG-tuned G Wagon engine at 101,500 miles on average, but can rear its ugly head at just 74,000 miles.

The second problematic sensor is the oil level sensor. When it goes bad, a trickle of oil can leak out, and even burn up on the hot engine, causing a steady cloud of obnoxious smoke. Nine owners of G500s from 2002 through 2008 reported this problem popping up at about 158,000 miles. Ten owners of G55 AMGs reported this problem on 2003-2011 SUVs, showing up as early as 7,700 miles.

Both problems sound frustrating. But honestly, an engine that’s smoking or not starting can be expensive to fix. A failed sensor is one of the easiest and cheapest possible causes to address.

Brake light switch failures

The boxy silhouette of a Mercedes G Wagon SUV with its headlights illuminated.
Mercedes-Benz G-Class | Aranprime via Unsplash

Finally, a brake light switch failure is another problem reported by multiple owners. Luckily this is a little electric switch below the brake light and when it fails, the SUV will light up a warning light on the dashboard. It is a relatively quick item for a technician or dealer to address.

Overall, 13 owners of Mercedes G500 SUVs, from the 2002 through 2008 model year, reported this. The average mileage before the sensor failed was 87,000. In addition, eight owners of 2003-2010 G55 AMGs reported the same issue.

So there you have it, several of the Mercedes G Wagon issues reported to the RepairPal website most often. For comparison’s sake, other SUVs have issues with dozens or hundreds of reported instances. RepairPal gave the G-Class SUV an “above average” reliability rating of 3.5 out of 5.

Next, find out about the cheapest G Wagon available or see more common G wagon problems in the video below:

You can learn all about the G-Class’s reliability in this next video:

You can see some of critic Doug DeMuro’s problems with the ergonomics and design of the last-generation G Wagon in this final video: