I drive Skoda Superb 2.0 TDI 150PS Y2019 with DSG DQ381.

Last couple of days I am occasionally strugling with "Gearbox in safe mode. You can drive on" message where the car is stucked in 2nd gear afterwards. After restarting the car, the message disappears and I could drive normally until it happens again after some time (for the instance, I drove 40km without any issues until it happened again).

I did a basic diagnostic and found fault code P174A00 - Valve 3 in partial Transmission 1 - electrical error (Passive/Sporadic).

Independent workshop suggested contact (harness) plate of the mechatronics should be changed (part no. 0GC927709A) as it looks like TCU is loosing connection with valve 3. This coud be replaced for around 200eur.

On the other side, Skoda of course suggested whole mechatronics replacement which is around 2000eur.

Should I give it a try with harness plate replacement?

Forgot to mention that I am on 90.000km right now without DSG oil change yet (somehow it should be changed at 120k per instructions). Also, I noticed that each time I had an issue with the mentioned fault code, car was driven for a while and it never happened before engine reached it's working temperature.

Sounds like a mechatronics issue, most likely you'll have 2,4,6 and Reverse, I had to have my mechatronics refurbed recently but due to a clutch position sensor. It's also the DQ381, my previous research suggests that as it's a lighter version of the DQ500 they're a bit more prone to issues.

No, it's stuck in 2nd gear only and it does not change to 3rd or 4th even if I reach 3500rpm.

Skoda official workshop won't bother with circuit plate change (this is a part of mechatronic itself) as they are saying only TCU or the whole mechatronic could be changed (the cost is around 1000eur or 2000eur respectively).

On the other side, unofficial workshop is willing to try with circuit plate replacement as there were cases where this was the reason of such fault code.

On 20/09/2025 at 19:22, Vrlorad said:

This coud be replaced for around 200eur.

For 200 Euro, definitely can't see a downside. I'd try it as it's alot cheaper than the 2K otherwise quoted.

Went today to Skoda for diagnostics, got info that mechatronics circuit (harness) plate should be replaced (they are confident 99% that should solve the issue).

Total cost of the repair is around 700eur (~300eur for the DSG oil, 270eur service fee, 27eur for the circuit plate 🙂and the rest for the other small parts).

2Y warranty provided.

I decided to go with offical Skoda dealer as I got info it's a bit tricky to replace the circuit plate since you need to be careful not to damage TCU. Also, there is a warranty offered unlike unofficial workshop.

Hopefully they are wright 🙂

On 25/09/2025 at 02:35, Vrlorad said:

wright

Right