Mercedes A Class (W169) CVT 722.8 transmission ECU problems

Mercedes A Class W169 CVT gearbox problems

This Mercedes A Class CVT (Continuously Variable Transmission) ECU is an extremely common problem for the 722.8 transmission. 

The root cause of this A Class gearbox problem is internal component breakdown of the ECU, commonly causing fault codes including: "0793 - The RPM Signal From Component Y3/9B4 CVT Secondary RPM Sensor Is Not Available" and "0722 - The RPM Sensor From Component Y3/9B5 CVT Output RPM Sensor Is Not Available", among others to be stored in the gearbox ECU. Faults with the output and secondary transmission speed sensor are also very common.

When the gearbox ECU fails, the vehicle will experience a loss of power, limp home mode and poor to limited gear selection. A warning message will also be displayed across the dash: Transmission Visit Workshop. 

This fault is not limited to only the Mercedes A Class gearbox ECU, these problems will also occur for the B Class CVT models.  

The usual solution for this CVT gearbox problem consist of replacing the gearbox ECU, valve chest, solenoids and subsequent coding. This can be avoided using our test and rebuild service, no need for subsequent programming as we retain the original coding. All we require is the gearbox ECU to resolve the 0722 and 0793 fault codes and eliminate the "Transmission Visit Workshop" display message.

Our rebuild option re-engineers the original manufacturing defects, meaning that the chance of further problems arising would be slim to none, but should any issues occur our lifetime warranty will ensure swift resolution of any problems. However, our work defect rate is lower than 0.6% on all of our rebuilds, so you can be assured of our very high standard of work.

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Common Failure symptoms:

  • Limp home mode / safe mode
  • Loss of power
  • ‘Transmission visit workshop’ warning message on dashboard
  • Transmission warning light on dashboard
  • Not selecting gears
  • Sticking in gear
  • Output speed sensor fault
  • Speed sensor fault


Common fault codes:  

  • 0722 - The RPM Sensor From Component Y3/9B5 CVT Output RPM Sensor Is Not Available
  • 0793 - The RPM Signal From Component Y3/9B4 CVT Secondary RPM Sensor Is Not Available
  • 0717 - The RPM Signal From Component Y3/9B5 (CVT Output RPM Sensor) Is Not Available
  • 0730 - The Gear Ratio In The Continuously Variable Automatic Transmission (CVT) Is Not Permissible
  • 1634 - Component Y3/9N1 (CVT (Continuously Variable Automatic Transmission) Control Unit) Is Defective Or The Voltage Supply Is Faulty


Affected Vehicles:  

  • Mercedes A-Class A150 / A160 / A170 / A180 / A200
  • Mercedes B-Class B150 / B160 / B170 / B180 / B200



Common Part Numbers - Shop Now


Test and rebuild: 

We test these problematic Mercedes CVT gearbox ECU’s under various, real-world load and driving conditions using our state of the art Hardware In-the-Loop (HIL) testing rig which will enable us to identify all internal faults. Our technicians will rebuild the transmission ECU and replace all common failing components with versions that are higher rated than standard, and then extensively re-test to ensure that no faults remain. This means that your rebuilt CVT gearbox ECU will perform as good as, if not better than a brand new replacement unit, ridding the Mercedes A Class of CVT gearbox problems once and for all.



This transmission control ECU is coded to the vehicle, however all original programming is retained meaning that once received back it is plug and play.



Our strict quality control: encompassing testing, components and workmanship will ensure only the highest level of work is carried out to meet our lifetime warranty standards. Due to our extremely high standards we work very closely with dealerships and specialists, offering a better solution to replacement.


Lifetime unlimited mileage*


How do I get my unit rebuilt?

Select your part number above and click: Get yours rebuilt

Print the payment/booking confirmation email.

Package the Mercedes A Class gearbox ECU inside a sturdy box with plenty of packaging material (make sure you include your confirmation email in the box).

Send us your package by tracked courier (the shipping instructions are on the confirmation email).

Once received we will test, rebuild and return your CVT transmission ECU with an unlimited mileage lifetime warranty. (if your unit turns out not to be faulty then we will refund your payment less a small testing fee and return shipping)


What if I don’t want to pay up front?

This is not a problem, if you prefer this option then follow the following steps:

Fill in and submit this test form.

Print the booking confirmation email.

Package the 722.8 gearbox ECU inside a sturdy box with plenty of packaging material (make sure you include your confirmation email in the box).

Send us your package by tracked courier (the shipping instructions are on the confirmation email).

Once received, we will test your transmission ECU and call you to advise on the outcome of testing, if your Mercedes A Class gearbox ECU is faulty and you choose to go ahead with the rebuild then we will take payment over the phone using a debit/credit card.

We will then rebuild your transmission ECU and return it to you with an unlimited mileage warranty.

If you require further information regarding this Mercedes A Class gearbox ECU then please contact us.

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Comments on "Mercedes A Class (W169) CVT 722.8 transmission ECU problems"
Daniel says: 24/09/2023 09:13:53
Good morning guy's I have a problem like the rest with my mercedes a class 2009. Ive been to the mechanic twice 1st time they said we need to change oil and filter and we did next day the same thing came up then called them again and the said it's the sensors fault.. we've changed that aswell. The very next day same problem again. Please can you guy's help me out and explain what's the real problem and how much it will cost?
ECU Admin says: 27/09/2023 10:22:01
Hi, we can certainly help. Please email us (contact us) your fault information, including fault codes and we can look into that for you
Godwin says: 28/08/2023 13:12:49
I have an a class CVT is having a problem how can you assist me where are you guys based can you give me a contact number thank you
ECU Admin says: 29/08/2023 09:43:36
Hi Godwin, we are based in Derbyshire. You can find our telephone and email on the following page:
Mo Agutu says: 03/07/2023 15:54:54
I have a Transmission visit workshop warning on my Mercedes Benz A180 (W169) dashboard. I took it to the dealership and they said the needed to replace the CVT module. Any help?
ECU Admin says: 05/07/2023 09:48:03
Hi Mo, sounds like you have been given the standard dealership response. Send our support team an email with your vehicle and fault details and we can help you out contact us
Mick says: 05/10/2022 11:45:18
I have a b class with this problem can you tell me price of repairs MIck
ECU Admin says: 06/10/2022 09:29:01
Hi, for rebuild prices select your part number from the following list
Johan Steyn says: 15/08/2022 17:17:00
Looks like the same fault, does not change gears, feels like the car is in limp mode. Where can I send the unit to be repaired ?
ECU Admin says: 16/08/2022 09:27:28
Hi, we can help with that. To get started just complete our Test Form:
Ovi says: 19/06/2022 22:33:46
I have a A200 elegance with the message visit garage transmission issues. How I can have my gearbox fixed? Thanks ovi
ECU Admin says: 22/06/2022 10:03:14
Hi, we would suggest having your vehicle scanned for fault codes. Once you have these we can then work out what is occurring
Marin gheorghe says: 06/06/2022 15:13:14
Pe panou de bord miapare transmision visit mercedes clasa a cat mar costa toata afacerea
ECU Admin says: 07/06/2022 10:17:30
Bună, pentru prețuri și informații despre livrare, vă rugăm să faceți clic pe butonul Magazin acum de mai sus
Simon Brady says: 20/12/2021 13:18:31
hi, i have the above gear box problems, how long does it take and how much does it cost?
ECU Admin says: 22/12/2021 10:08:31
Hi Simon, select your part number above for prices and shipping information. Our turnaround is currently 2-3 working days
Andre Johannes says: 27/08/2020 11:53:40
I would like to get my old part fixed. How do we go about it Kind regard Andre
ECU Admin says: 02/09/2020 10:42:44
Hi Andre, please select your part number above or complete our test form to get things started:
Vitor Almeida says: 30/10/2019 23:27:32
Hello! I have MB A200 and I have this malfunction 0657 The voltage supply of the electromagnetic control valves in the continuously variable automatic transmission (CVT) is defective. Any answers to this? Thanks best regards
ECU Admin says: 06/11/2019 15:10:37
Hi Victor, the best answer we can give is that the CVT gearbox ECU appears to be faulty. We offer test and rebuild on these units, for more information please select your part number from the following link:
Janus says: 15/10/2019 08:10:33
Limp mode 1st gear and reverse.Have power but don't select any gears
ECU Admin says: 16/10/2019 09:55:20
Hi Janus, you may be experiencing a fault in the CVT transmission ECU especially if your fault codes match those we have listed. For information on rebuild prices and shipping information just select your part from the following list:
Martin says: 04/09/2019 13:52:11
I have a b200 cdi With comes up with this code 0793 , 0722 , 0896
ECU Admin says: 04/09/2019 15:19:37
Hi Martin, thank you for your comment. Looks like you may be having issues with the transmission ECU. We can test and rebuild that for you, for prices and shipping information please select your part number above or find it here:
Amos Mkandawire says: 08/09/2019 13:39:34
I have a problme with my merc B170.Shows the massage transmission consult workshop .
ECU Admin says: 09/09/2019 11:53:56
Hi Amos, we would advise to scan the vehicle for fault codes. If your fault codes match what we have listed then you would be looking at a faulty B-Class transmission ECU. We can offer test and rebuild on this, find your part number here:
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