What’s the difference between a Kess 3 slave and a Kess 3 master tuning tool? In this article we look specifically at the KESS3 Master vs Slave Tuning Tools.
What is Tuning?
Tuning also known as engine remapping is the process of modifying a vehicle’s software held on the engine control unit (ECU) to improve its performance and / or fuel economy. The process is done through the use of tuning tools, which enable the vehicles software to be copied from the ECU.
The Alientech Kess is designed for this exact purpose. There two types of Kess3 tuning tools, master tools and slave tools. Here are the main difference between the Kess 3 master and the slave tool option.

Alientech Kess3 Master
The master Alientech Kess3 is designed to be used by trained professionals in a workshop / dyno setting. The master kess3 is a little more expensive. And offers a wider range of features and capabilities compared to slave tools. They are typically used to write new software onto the ECU. Hence allowing for the modification of a wide range of engine parameters such as fuel injection, ignition timing, and boost pressure.
Software can be written onto the ECU to modify fuel injection parameters, ignition timing, boost pressure. As well as many other engine parameters.
In addition to writing new software onto the ECU. The Alientech Kess 3 can also be used to clone many types of ECU’s too
The slave kess3 is designed for use by non-professional enthusiasts. They are typically cheaper and less feature-rich than master tools. Rather than being able to write new software onto the ECU. Slave tools are used to read and modify existing software. This means that the range of engine parameters that can be modified is more limited compared to a master tool.

Alientech Kess3 Slave
The Slave Kess3 is often seen as easier to use than the master option. While the physical process is reading and writing the software to teh ECU is the same on both options. The Slave tool uses new ECU files written for the tool. As such the operator does not need to write their own tuning software.
This can make it an ideal tool option for those new to tuning. Or those that simply don’t want the hassle of writing their own tuning files.
So, what’s the difference between a Kess 3 slave and a Kess 3 master tuning tool
- KESS3 Price: As mentioned, the Alientech master kess3 will cost a little more than the slave version.
- KESS3 Capabilities: The master Kess3 offers a wider range of capabilities. Including the ability to write new custom and bespoke software for the vehicles ECU.
- Professional use: the master Kess3 is primarily used by trained professionals in a workshop and dyno room setting. Not only writing and developing tuning software for their own use. But in most cases supplying software files to dealers and tuners operating the slave tool set up.
- Where as, the Slave kess3 is tuned by those that don’t want to write their own custom software. But have the convenience of ready to use and load software being provided.
If you are not sure which KESS3 option is right for you. Get in touch with our support team via phone on + 44 (0) 1789 774444 or send us a message via the form on our contact page and we will talk through your options. We also offer free no obligation training and demonstration sessions which you can request by contacting us too, our UK headquarters is based in Warwickshire – Get directions – Contact us
You can see the full range of Alientech Kess3 tools and protocol options here in the Alientech Tuning. Shop : Alientech Kess3
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FAQs on the Difference between a Kess 3 Slave and a Kess 3 Master Tool
What is the main difference between a Kess3 Slave and a Kess3 Master tool?
The main difference between a Kess 3 slave and a Kess 3 master tool is how they handle your vehicles software files. The master tools reads “open” (unencrypted) files which you can open, look at and edit yourself or send them to the tuner of choice for modification. Whereas the slave KESS v3 reads “locked” (encrypted) files, which you cannot open or edit yourself. You can only send this to your chosen “Master” who is the only person who can decrypt and provide a modified file for you.
Are the Kess3 Slave and Master tools physically different or cover different vehicles?
No, the KESS3 master and slave tools look exactly the same with the same connectors and cables. They have the same protocol options and can tune the exact same list of vehicles.
Can I upgrade my Kess3 Slave tool to a Master tool?
Yes you can upgrade your KESS3 Slave to be a KESS3 Master automotive tuning tool. All you need to do is pay the difference in the price for the master activation protocols. The only thing you need to be aware of is that your current “Master” must agree and allow the upgrade.
Where can I purchase Alientech Kess3 tuning tools?
You can purchase the full range of Alientech KESS3 from our Alientech Tuning online shop by clicking here – https://www.alientech-tuning.com/product-category/kess-3-tuning-tools-and-software/kess3-slave/