Table of Contents
KESS3 can now read, write and clone the Bosch ZF AL552 / 8HP55 gearbox computer. Alientech added it in Upgrade 3.37 on the 24th of July 2026. This KESS3 protocol update covers Audi, Porsche and Volkswagen models from 2016 onwards. Because it clones, a failed unit can now be swapped in your own workshop instead of at a main dealer.
What The New Protocol Lets You Do
A transmission control unit, or TCU, is the computer that runs an automatic gearbox. It decides when to change gear, how fast the clutches engage and how much engine torque it will let through before cutting power to protect itself.
Upgrade 3.37 gives you three operations on the AL552:
- Read – copy the software out of the unit, so you have a backup
- Write – put modified software back in
- Clone – copy everything from one unit onto a second identical unit
All three run in bench mode. You can connect straight to the TCU connector, without removing the TCU from the vehicle, where access allows. You don’t have to open the case, which is the difference between bench mode and boot mode. Learn more about the differences in our guide to bench, boot and OBD tuning.
Which Cars Have This Gearbox
Alientech lists the protocol as covering VAG vehicles built from 2016 onwards.
| Make | Models |
| Audi | A4, A5, A6, A7, A8, Q5, Q7, Q8, S5 |
| Porsche | Cayenne |
| Volkswagen | Touareg |
The engines are the 55 TFSI (3.0 V6), the 45 TDI and the 50 TDI (3.0 V6).
AL552 (VAG’s part code) and 8HP55 (ZF‘s model name) refer to the same transmission, which is why service records use them interchangeably.
Why Cloning Saves A Dealer Visit
This update lets you make money by turning what used to be an expensive dealer job into a simple task in your own workshop.
When an AL552 unit fails electrically, a replacement part arrives with blank factory software. It doesn’t have the car’s identity, doesn’t match the immobiliser security system and it lacks the car’s saved operating data. Installing it as-is causes the car to reject it, which previously required paying a main dealer to code it.
Cloning solves this in three steps:
- Read the old unit on your bench to pull its data out.
- Write that extracted data directly onto the new replacement unit.
- Fit the replacement unit into the car.
Because the car recognises its original data, it accepts the replacement and drives normally.
Important Warning: The old unit must still be readable. If it has severe water damage or a failed power stage, the memory chip inside is dead and its data cannot be recovered. Always try reading the old unit before ordering a replacement.
Tuning The Gearbox After An Engine Remap
If you remap your engine without touching the gearbox, the two systems could end up fighting each other.
The factory TCU (Transmission Control Unit) has a built-in torque limit designed for standard power. Once you exceed that limit, the gearbox steps in and cuts your extra power to protect the clutches. Plus, the factory shift points are calibrated for stock power, meaning the car could hold gears at the wrong RPMs.
When you tune the TCU as well, it raises that torque limit and optimises the shift points. This ensures that your gearbox works with your new engine tune and doesn’t hold it back.
What You Need Before You Start
A bench power supply
Because the control unit is disconnected from the vehicle’s electrical system, an external power source must be provided. A voltage drop during a write operation will corrupt the firmware and brick the unit. The KESS3 bench power supply maintains constant voltage throughout flashing,
The right cable
Bench work runs through the KESS3 multiwire cable, a set of numbered wires you place into the correct pins on the unit’s plug. The TCU extensions reach gearbox connectors, which are laid out differently to engine ECU ones. KESS3 shows you the pinout on screen before you connect, making this process simple and easy to do.
The right protocol licence
Bench protocols are sold separately from OBD protocols. A tool licensed for OBD alone will not open the AL552, even with the cable attached. Master users need the relevant KESS3 Master protocols. Slave users upgrade through the Car and LCV bench-boot package. You also need an active KESS3 subscription as this gives you access to the latest protocols.
AL552 Or AL551? Two Updates, Two Days Apart
Alientech released a second gearbox protocol two days before this one. The names differ by a single digit, here’s a breakdown of the differences.
| AL551 (Upgrade 3.36) | AL552 (Upgrade 3.37) | |
| Released | 22 July 2026 | 24 July 2026 |
| Connection | OBD port, unit stays in the car | Bench, unit is connected directly or comes out |
| Operations | Read, write | Read, write, clone |
| Model years | 2008 onwards | 2016 onwards |
| Audi | A6, A7, A8, Q5, Q7, Q8, RS6, RS7, SQ5 | A4, A5, A6, A7, A8, Q5, Q7, Q8, S5 |
| Other makes | VW Touareg | VW Touareg, Porsche Cayenne |
| Tools | KESS3 and Powergate | KESS3 |
In short: a 2013 Touareg can be done through the diagnostic socket with the gearbox still in the car. A 2019 Q7 needs a direct connection to the unit, or to have the unit removed and on the bench.
What This Protocol Will Not Do
Alientech’s notes for Upgrade 3.37 cover reading, writing and cloning. They say nothing about VAG Component Protection or immobiliser functions and there is a key reason for this.
- Component Protection is a VAG security system that locks certain replacement parts to one specific car. It is cleared across several control units using manufacturer diagnostic access, so a bench read of the gearbox computer does not touch it.
- Cloning an AL552 and clearing a Component Protection flag are two different jobs. Treat them as one and you end up with a car that will not start.
Which Other Tools Support It
KESS3 covers AL552 units from 2016 onwards through Upgrade 3.37.
Magicmotorsport’s FLEX also offers bench access to the AL552, but only the Gen2 versions fitted from 2022 onwards. So a 2017 Q5 gives you one option and a 2023 car gives you two.
Learn more about KESS3 vs Magic Motorsport Flex in our comparison guide.
Getting Upgrade 3.37 On Your KESS3 Tuning Tool
To get the 3.37 upgrade on your KESS3 tuning tool, go to the Alientech Suite. Connect your tool, let it synchronise, then select the vehicle and the protocol appears.
If nothing shows up, check three things in this order:
- Your subscription is active
- Your protocol entitlements cover Car and LCV bench-boot
- Your tuning tool is talking to the Suite
Our guide to fixing KESS3 connection errors covers the usual causes.
New to bench work? We have a wide range of Alientech training courses to help you.
Why Choose Alientech Tuning
We are a UK-based authorised Alientech reseller and part of VIEZU Technologies Ltd. You get genuine KESS3 Master hardware, access to the latest protocols and support from people who use Alientech tuning tools daily. Counterfeit KESS3 units never receive updates. A cloned tool cannot synchronise with the Alientech Suite.
If you’re not sure whether your tuning tool can run the AL552 bench protocol, get in touch and we will help you.
About The Author
Simon White is Technical Director and Managing Director of VIEZU Technologies Ltd, the parent company of Alientech Tuning, and lead trainer at the VIEZU Technical Academy. He has around 20 years of real-world tuning experience and holds EVC-Certified Trainer status, listed on the official EVC academy database.
Bosch ZF AL552 / 8HP55 FAQs
Which vehicles use the Bosch ZF AL552 / 8HP55 transmission control units?
Vehicles that use the Bosch ZF AL552 / 8HP55 transmission control unit are VAG models from 2016 onwards. That covers the Audi A4, A5, A6, A7, A8, Q5, Q7, Q8 and S5, the Porsche Cayenne and the Volkswagen Touareg. The engines are the 55 TFSI (3.0 V6), 45 TDI and 50 TDI (3.0 V6).
What is the new bench protocol for the Bosch ZF AL552 / 8HP55 TCU?
Alientech released a new KESS3 bench protocol update (Upgrade 3.37) on the 24th of July 2026. This update means that you can read, write and clone the AL552 through the unit’s own plug, with the gearbox computer out of the car and powered on a bench.
Which major tuning and hardware platforms support this bench protocol?
KESS3 supports it through Upgrade 3.37, covering units from 2016 onwards. Magicmotorsport’s Flex offers bench access to AL552 Gen2 units from 2022 onwards. The two are not interchangeable and each needs its own licences and cables.
Can this bench protocol be used to clone a faulty TCU onto a replacement unit?
Yes, this KESS3 bench protocol can clone a faulty TCU onto a replacement unit, as long as the faulty unit still reads. Cloning copies the old unit’s data onto the replacement unit, capturing all of its historic data so the car accepts the replacement without needing you to visit the dealer. Always read the old unit before ordering the new one.
Does this protocol bypass VAG Component Protection and Immobiliser restrictions?
No, this 3.37 upgrade covers reading, writing and cloning. Alientech makes no claim about Component Protection or immobiliser functions. Those are cleared across several control units with manufacturer diagnostic access, not through a bench read of the gearbox computer.
Do I need a new cable to use the AL552 bench protocol?
Yes, you will need the KESS3 multiwire cable plus the TCU extensions to use the bench protocol.
Will the protocol appear on a KESS3 with a lapsed subscription?
No, new protocols arrive through the Alientech Suite and you need an active subscription to get access to the latest upgrades. If you renew your KESS3 subscription then your tuning tools will synchronise and you’ll see it as long as you have Car and LCV bench-boot protocols.