If you are looking at a MK4 and it has the dreaded CEL and P0420 code, you’re looking at a big chunk of the purchase price to replace it. You’ll have to fork over the money to replace it, which isn’t cheap. Since these cars were equipped with catalytic converters, it is illegal to just straight pipe it.
Basically, that means your catalytic converter isn’t converting enough of the harmful gasses in your exhaust to less harmful ones and your post-cat o2 sensor is picking up higher than normal readings.
Generally, you’ll see that P0420 code and a CEL illuminated that indicates your catalyst efficiency is below the threshold. However, according to The Humble Mechanic, catalytic converter failure is/was common enough on MK4’s that it’s worth mentioning. Ok, this isn’t MK4 specific, because catalytic converters regularly fail after a certain point in pretty much every car. A simple replacement MK4 brake light switch is all you need. This is the most updated version, so if your brake lights either won’t come on, won’t turn off, or you can’t get your automatic MK4 out of park, it’s likely the culprit. The original switch was exchanged for a purple switch, which also failed, and then finally with a green colored switch. There were so many instances of brake light switch failures from an early point in the MK4’s introduction that multiple recalls were issued. The brake light switch is another inconvenience, as this switch tells your brake lights when to illuminate once you’ve hit that middle pedal. Regardless, we have all the MK4 window regulator parts from Genuine VW for you here. Again, this happens to all windows, two or four-door models, and you should check them all if you have one fail. There are a few possible fixes here, but it’s best to just replace everything while you’re in there. This usually requires either a new cable or an entirely new regulator unit. If some go, the others aren’t far behind.Īdditionally, the regulator cable itself is known to bind and tangle, causing the regulator to completely fail.
They are easily replaced, but you should check all your windows if you have some fail. Common problems were the plastic clips that hold the window glass on its track, which would break or crack, and cause the window to not function properly. This issue was generally fixed under warranty, but that doesn’t mean it’s fixed forever. Even when the MK4 was new, it was common for owners to experience one or two different failures with their power windows. Like all European cars of this era, the window regulators are a usual pain-point for MK4 owners.
Today, we’re going to address the common Volkswagen MK4 problems and failures. Those offered significant performance increases, but all models suffer some common problems buyers’ should know before they set out to grab one for themselves. Even today, the MK4 is still considered relevant among enthusiasts, especially in the GTI trim or R32 trim. With several engine options, layouts, and even models to choose between, it’s no wonder they were so prolific. The Jetta, Beetle, and Golf all shared the MK4 platform from 1998-2005 (give or take, some versions started later, others ended later). The MK4 platform is one of the best-selling VW models of all time, especially if you include all the possible variants.