Mechanical Diagnostics
7 SPEED DQ200 MECHATRONIC
Customer reporting some issues with their DQ200 7 speed transmission on a 2016 Golf TSI Bluemotion. Specifically with the following Symptoms:
- Shuddering in heavy traffic
- Slight shuddering from stop (when at stop light)
- Car won’t go into gear from Park. (customer would turn off car and on again, to get it moving).
- Delayed movement when shifting from P to D or R to D and vise versa. (feels like car is in neutral).
Overview
We decided to tackle this issue and diagnose what the cause might be. As it is well known that this line of transmissions is known for their issues, specifically the mechatronic units.
So we sat with the customer to discuss a bit more on the symptoms. This is when the customer specified that at one point a check engine light appeared, and when he checked the code using a generic OBD2 reader, something along the lines of (Transmission Fluid Pressure Sensor) error appeared, no other details where provided. So he cleared it and kept driving the car for a couple days until it happened again and some of the symptoms appeared without any check engine lights this time around. This is when he came to us.
Testing
So we did a look over and scanned the car for any codes. Nothing out of the ordinarily appeared and the scan came up with nothing.
We took it out for a test drive to try and replicate the symptoms described but where only able to feel a very slight shuddering when driving from a stop, nothing to make us nervous though. The test drive encompassed all the scenarios the customer would have gone through that ranged for about 40KM. But sadly nothing came out of it.
We informed the customer to leave the car with us so we can test drive it after it cooled off for a bit. On the second test drive the next day, the symptoms described by the customer appeared but only after about a 70KM drive while pushing the car hard and driving it normally every so often.
Right after the symptoms appeared we got a check engine light and (error gearbox) on the infotainment system, the code from the check engine light was 17225/P0841 which was related to the mechatronic unit, BINGO!
Going back to the history of the car the customer informed us that the mechatronic unit was replaced under warranty years ago by the dealer for completely failing.
Diagnostics
Now that we know its the mechatronic unit, we start the Diagnosis, First thing to do with code 17225 is to check the mechatronic wiring and pressure sensor, which turned out to be all fine.
Then we went ahead and tested the mechatronic system pressure & fluid, the system pressure was a bit below normal and the cause of this for some odd reason was the fluid, when drained (taking into account the residual fluid left inside the accumulator unit) it measured a lot lower than the OEM recommended level and very dirty (Original Color is Green). There were no leaks present at all, the customer also informed us that he never had any issues or leaks at all.
Old Mechatronic Fluid
New Mechatronic Fluid
According to Volkswagen the Mechatronic is a non serviceable unit, in this case if anything goes bad, Volkswagen needs the whole unit back, and they send you a new unit that is already prefilled to install. This can get quite expensive, but we have worked on Mechatronic Units before and this is a simple procedure to clean out the old fluid and refill it with new fluid making sure its to the manufacturer’s recommended amount.
The issue here is that the mechatronic unit was low and VERY dirty. We also took the opportunity to replace the transmission fluid too. Which takes about 1.7 Liters of Fluid. The Mechatronic Unit take 1 Liter of fluid.
Conclusion
Simply Replacing the Mechatronic Fluid and Transmission Fluid solved the issue for this customer. The reason this all started was because the fluid inside the mechatronic unit was very dirty and low, this could have caused issues with the pump which in turn gave the error reading when the check engine light appeared.
The customer has been driving his car ever since with no issues or symptoms for the last 1,000KM now.
Final Thoughts
I am not sure why volkswagen states that this is a non serviceable unit, the same goes with the fluid for the DQ200 Transmission, both fluids where dark to the point of no recognition on what the original color of the fluid is, the customers car has only done 60,000KM when these issues started happening.
My Recommendation, is change the transmission fluid every 40,000 – 60,000 KM to insure a longer life of the transmission and its components.