process
Repairing the gearbox control unit – for DSG, VGS and TCU
Whether it is heavy jerking when pulling away, implausible shift shocks or the complete failure of reverse gear — a defective transmission control unit (TCU/TCM) makes driving a torment and endangers the gearbox. The Mercedes VGS 722.8, the 9G-Tronic (725) and the VAG DSG transmissions DQ381 and DQ500 are particularly affected. Save yourself the expensive complete replacement from the manufacturer! Revonik GmbH repairs your control unit at component level — fast, reliable and up to 70 % cheaper. Including a 24-month warranty. With the original unit, vehicle-specific data is retained in many cases. Coding, basic settings or further work on the vehicle may nevertheless be required, depending on the vehicle and the repair. For private and commercial customers.
Your benefits with
Transmission control unit repair
Harsh shifts, limp-home mode or missing gears can have electronic, hydraulic or mechanical causes. Revonik checks whether a transmission control unit listed in the product database is a possible source of the fault and whether a repair makes technical sense.
Isolating the cause before replacing parts
Jerking, limp-home mode or missing gears can have several causes. The complete fault memory is therefore the basis of every inspection.
Targeted electronics testing
We test transmission control units for relevant internal defects, communication problems and electronic component faults.
The original unit as an opportunity
If the original unit can be repaired, vehicle-specific data is often retained.
Avoiding costly replacement
A technical inspection helps to avoid ordering a spare part before the actual cause has been established.
Complete case details
The part number, transmission type, fault codes and precise shifting symptoms reduce follow-up questions and simplify identification.
Express only where genuinely suitable
Standard repairs generally take 2–4 working days. A 48-hour express service is only possible for suitable standard faults, at extra cost and after confirmed capacity.
24-month warranty
A 24-month warranty applies to the repair service performed, under the approved terms.
Full transparency –
no hidden costs:
What does the
inspection include?
We will check your control unit for the causes of faults. The diagnostic fee will be deducted in full from the cost of any repairs.
What is hardware repair?
Repair of faulty speed sensors, pressure sensors, solenoid valves and faults on the circuit board.
Data transfer / cloning
If the control unit is beyond repair (e.g. due to a major oil leak), we will transfer your original vehicle and immobiliser data exactly as it is to a replacement unit.
What happens if it is irreparable?
We are offering you a fully reconditioned replacement unit that we have pre-programmed. You won’t need to have it programmed – simply fit it and you’re ready to go.
Typical symptoms and error codes
Does your automatic gearbox shift jerkily, cause the engine to stall, or switch straight to emergency mode? Often, the problem lies not with the mechanical gearbox itself, but with the control unit (TCU). Here are the most common faults that we fix every day at our diagnostic centre in Kerpen:
- P0717 / 0722: The speed signal from component Y3/9b5 (CVT output speed sensor) is not available
- P2722 / P2731: Unauthorised engagement of the hydraulic brake/clutch when the gear selector is moved to the „N“ position“
- P0720: Output speed sensor malfunction
- P0793: Intermediate shaft speed sensor circuit – No signal
- Symptoms: Severe gear-change jolts, jerky gear changes, the engine stalling when setting off, fluctuations in revs, inability to move forward.
- P073E00: Reversing gear signal fault
- P07B700: Pressure sensor, signal implausible
- P07EF00 / P07E400: Park position cannot be engaged
- P07B571: Solenoid valve for parking lock
- P1735: Clutch position sensor 1 – electrical fault
- P1736: Clutch position sensor 2 – electrical fault
What happens if you ignore the defect?
Risk of mechanical damage to the gearbox
A faulty control unit sends the wrong signals to the clutches and valves. This leads to enormous mechanical wear and tear in the gearbox. What starts out as a relatively inexpensive electronic repair can quickly turn into major gearbox damage (cost: €4,000 and upwards).
Sudden breakdown
Errors such as P07E400 (parking gear cannot be engaged) or a failure of the speed sensors can cause the vehicle to come to a standstill in the middle of a junction or on the motorway.
Expensive new purchase directly from the manufacturer
An authorised workshop does not repair circuit boards. They will always sell you a completely new gearbox control unit – including expensive removal and fitting costs, as well as software programming.
Loss of vehicle value
A gearbox control unit that has not been repaired will have a negative impact on your vehicle’s resale value. Keeping it in good condition is crucial for maintaining its value.
The consequences if
you do not have your unit repaired:
Do not ignore gear-changing problems or error messages. A faulty gearbox control unit leads to extreme mechanical wear, sudden breakdowns and, in the worst case, catastrophic gearbox damage. What can still be repaired today as an electronic fault could cost you thousands of euros for a new gearbox tomorrow. Avoid unnecessary risks – start your repair order now.
This is how we repair your control unit
Diagnosis & Removal
Have the fault memory read out at your garage. Print out the fault report and have the gearbox control unit removed by a qualified mechanic.
Order & Shipping
Please fill in our online form. Important: Please print out the order confirmation or email and enclose it with the parcel, along with the error log. Pack the device securely (make sure to degrease it thoroughly beforehand) and send it to us.
Inspection & Repair
Once we have received the item, we will carry out a diagnostic check (subject to a charge). Once you have given your approval, we will start the repair (standard turnaround time: 2–4 working days). For standard faults, an express repair (48 hours) is also available for an additional charge.
Payment & Returns
Once the repair has been successfully completed and payment received, we will return the device to you securely packaged (postage: €14.90 incl. VAT)
Installation
Simply install it, top up the transmission oil and drive off. With the original unit, vehicle-specific data is retained in many cases. Coding, basic settings or further work on the vehicle may nevertheless be required, depending on the vehicle and the repair.
Select repair
Frequently asked questions
On this page you will find answers to frequently asked questions
about control unit repair.
How do I recognise a possible problem with the transmission control unit?
Indications can be limp-home mode, harsh shifts, delayed gear changes, a missing reverse gear or error messages. These symptoms do not prove a control unit fault; sensors, mechatronics, oil level or mechanical components can equally be the cause.
Which data do you need for the inspection?
Please send the vehicle data, the transmission type, the control unit part number, the complete fault codes and a short description of the driving behaviour. A diagnostic report is particularly helpful.
Does a transmission control unit have to be adapted after the repair?
That depends on the vehicle, the transmission and the type of repair. If the original unit is repaired, reprogramming may not be necessary; basic settings or adaptation drives can still be required.
Does Revonik also test replacement units?
Please enquire before shipping, stating the part number and a description of the fault. We will then assess which service makes sense for the specific unit and vehicle.
