A-Class Automatic Gearbox ECU

A-class transmission ECU fault

This is a common problem for all Mercedes A-Class vehicles built after 1998 with FTC automatic transmission, this will cause the “F” light to appear on the dash and the gears will feel as though they are “banging” in to place.

Other common running issues that a faulty A-Class transmission ECU will cause include sticking in gear or failure to select forward or reverse gears, forced limp home mode and even complete non-start of the vehicle.

You may experience one or several of these symptoms as they often begin intermittently but will undeniably progress into a permanent issue if not rectified.

On seeing these issues you may opt for a replacement unit to solve the problems. However, the transmission ECU is not available to purchase separately from the valve chest and solenoids which makes it very expensive to replace. This will also incur programming costs as this unit must be coded to your car.


We offer a more favourable solution: a test and rebuild of your FTC transmission ECU. With this option you will not need to recode the ECU once it is back from us.


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Common Failure symptoms:

  • ‘F’ warning message on dash
  • Banging into gear
  • Sticking in gear
  • Failure to select gear
  • Limp home mode
  • Non-start


Common fault codes:

  • P1840 - Valve Y3/7Y1 Pulse Width Modulated Solenoid Valve 1/4 Fault
  • 2123 - Y3/7Y5 Pulse Width Modulated Solenoid Valve Shift Pressure Is Defective
  • P1858 - 2227 - Starter Contact Defective
  • 2531 - Shift Valve 1/4 or 2/5 Jammed In Push Position Shift Valve Pressure Too High.


Affected Vehicles:

  • Mercedes A-Class range 1998-2007 (1st and 2nd generation with FTC transmission)


Part number location:

A-Class transmission failure

A-Class transmission fault A-class FTC part number


Test and rebuild:

Each FTC transmission ECU is comprehensively tested on our bespoke Hardware In-the-Loop testing rigs under real-world loads and driving conditions both before and after the rebuild. During the rebuild we use only the highest rated components so that once fitted back onto the vehicle the transmission ECU will outlast the vehicle.



This transmission ECU is coded to the vehicle, during test and rebuild all programming is retained.



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*


Price and product info: A-Class transmission ECU range


How do I get my unit rebuilt?

To pay for the rebuild select your part number and click: Get yours rebuilt

Print the payment/booking confirmation email.

Package the Mercedes A-Class FTC transmission 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 A-Class 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 Mercedes A-Class FTC transmission 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 A-Class transmission ECU and call you to advise on the outcome of testing, if your unit 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 FTC transmission ECU, then please contact us.

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Comments on "A-Class Automatic Gearbox ECU"
Helene says: 13/08/2023 07:05:10
What does it cost to repair the ECU unite.
ECU Admin says: 14/08/2023 09:51:54
Hi Helene, for the latest prices please click Shop Now above or follow this link: https://www.ecutesting.com/product-catalogue/mercedes/a-class/ecu-transmission/etm454932/
Monde says: 03/04/2023 13:25:38
My Aclass doesn't change gears and it's shows f sign.
ECU Admin says: 04/04/2023 09:36:42
Hi, these are common symptoms of a faulty FTC unit. We would advise to scan the vehicle for stored fault codes that will give an indication to the cause of the issue before removing any part from your vehicle
Rob says: 24/03/2021 10:27:43
Merc a 160 automatic 2003 .Fault Y3/7y1 Solenoid valve 1/4 shift defective .Stuck in 2nd on start up .But I put into neutral re start the car and it is in 3 rd then shifts up to 5 th and back to 3rd without probs but won't go to 2nd or 1st .What's the problem , solenoid maybe .Thanks
ECU Admin says: 25/03/2021 09:16:31
Hi Rob, as you can see above this is a common fault with the transmission ECU. We can help with this if you would like to send us your part: https://www.ecutesting.com/product-catalogue/mercedes/a-class/ecu-transmission/
Matt Jones says: 20/03/2020 18:11:59
My a160 automatic gearbox has a issue..the rpm component y3/9b4 is not working properly.. think it's the rmp sensors
ECU Admin says: 24/03/2020 10:09:52
Hi Matt, from the fault code that you are getting it looks like you may have the 722.8 gearbox, we can help with that transmission ECU too, please see the following information: https://www.ecutesting.com/common-faults/mercedes/mercedes-a-class-w169-cvt-gearbox-problems/
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