Common Faults in the 6-Speed DSG Gearbox Automatic Transmission

The transverse six-speed DSG gearbox transmission, also known as DQ250, is a dual-clutch automatic transmission that is found in vehicles by a number of manufacturers. These manufacturers include Audi, Volkswagen, Skoda, and Seat. The DQ250 is a dual-clutch transmission that employs a combination of manual transmission gears and automatic transmission clutches in order to gain the benefits of both.

This particular transmission is old news, having been replaced by newer versions, but it has been used in so many vehicles that are still on the road today that it is most definitely still relevant.

So, what happens when this very popular transmission goes bad?

A traditional automatic transmission uses a number of clutch packs to produce the desired output ratio. This works fine, but it has drawbacks, one of the biggest being fuel efficiency. Conversely, manual transmissions use solid metal gears and a single manually operated clutch. This setup creates less resistance and better fuel efficiency, but it means the driver has to deal with pesky clutch pedals and gear levers.

DSG Gearbox

DSG stands for Direct-Shift Gearbox, and it incorporates the best of both worlds into its design. Using an advanced electro-hydraulic control module to control clutch application and gear shifting, the DSG gearbox can bring the driving comfort of a full automatic to the table while still getting the greater efficiency of the manual-style gears. Furthermore, it makes use of a dual clutch assembly, where one clutch is responsible for even numbered gears and the other for odd-numbered gears, improving shifting quality further.

Juddering/Shuddering

Before we get into the transmission fault here, there is another cause of juddering which is far more common, and it is outside of the transmission itself. If you experience the juddering mainly when you start the engine and when the car is idling, often accompanied by a loud clattering noise, the problem is likely in the dual mass flywheel which sits between the transmission and the engine.

The flywheel consists of two plates that can move a small amount in relation to each other. This provides a cushioning effect when torque is transferred from the engine to the transmission. When that flywheel wears down, and the amount of movement is too great, you get a juddering/shuddering sensation.

It’s important not to leave this fault for too long. If the two flywheel plates sheer off from each other, your vehicle will lose drive entirely. If your flywheel is fine, however, and the juddering sensation is most noticeable on gearshifts—particularly at lower speeds—the problem likely lies in the dual clutch assembly. Unfortunately, it’s a simple matter of wear and tear, and there’s not much to be done for it other than replace it.

Mechatronic Failure

Default Mode—also known as limp mode and failsafe mode—is a failure state of the transmission where it detects a fault and limits itself to one gear (typically third) to limit damage to the transmission. This will often be accompanied by an indicator on the dashboard, such as flashing “PRNDS” lights. If your transmission has gone into default, there will be trouble codes in there to explain why it’s done this. You’ll need to get your vehicle scanned with a good diagnostic machine to find out what those codes are.

If the codes mention “clutch limits reached” (or something similar), there’s a good chance the problem is your clutch. Typically (though not always) this won’t occur until after the aforementioned juddering/shuddering fault. If the codes mention “adaptations,” it’s possible that your problem may be fixed with an adaptation reset. You’ll need to find someone with a good VAG diagnostic tool for this.

DSG gearbox Failure

If the codes mention any sensors, gear ratios, or unexpected mechanical disengagements, the problem is almost certainly your mechatronic. The mechatronic is the name given to the electro-hydraulic control unit that is responsible for controlling the gearbox, and it’s a very expensive lump. Fortunately, there are many companies that can repair this fault, and a quick search of “DSG Mechatronic Repair” should yield plenty of results. It should be noted, however, that these companies are limited in what they can test for and repair in these mechatronic units.

I have been involved in a number of situations where the repair company tested the mechatronic and found to be “ok,” yet the fault was eventually cured with a replacement mechatronic. Bear in mind, with these repair companies, “tested ok” means they couldn’t find a fault. Not that there’s nothing wrong with it.

One particularly common symptom of a faulty DQ250 mechatronic is a partial or total loss of reverse, so be on the lookout for that as a strong indicator that the mechatronic is failing.

Noisy Bearings

The mechanical workings of the DSG gearbox —the physical gears and syncros—don’t tend to fail very often in my experience. I have seen a number of instances of bearings wearing down, however. This typically results in a metallic noise when driving.

I have known DSG transmissions with this symptom to be driven for quite some time with no ill-effects other than quite irritating driving noise. However, I most definitely wouldn’t recommend you leave this problem unattended. If the mechanical components of the DSG gearbox did fail, it would be pretty catastrophic for the transmission.

The fix is a bearing kit, assuming the problem is dealt with promptly, and no other damage has been caused.