How to solve KESS V2 V5.017 and Ktag V7.020 error reading Magneti Marelli

I just bought KESS V2 V5.017 and Ktag V7.020 Master Clone from a vendor recommended by a friend. Both are reformed by the seller to ensure proper operation. At all times the vendor has been very serious and the friend who recommended it to me assured me that it was trustworthy

When I got both interfaces, the vendor made his installation.
All very well up there, but when I try to read the first 2 control units (Magneti Marelli 4MV and 4BV) which I have urgency to read, in none of the cases was it possible to read.

I put the details of the procedure below:

  1. Procedure with Magneti Marelli 4MV Skoda fabia 1.4 Engine: BBY
    Tool used Kess V2 using OBD2

This first reading was done in bank, proceeded with the pin-out correctly
The first error I receive is:

Warning, unknown ECU. For a correct procedure you must send log files and Reading to the technical support. Proceed anyway?


When giving OK, the program managed to read me the HW information
HW: MARELLI Boot 4MV r06
Upg. SW 036906034FD 4823

Then the next poster is:
Error while transferring data in Reading

Modify the speed of reading with each one of the variants that the Kess brings, but all in vain

Then connect directly the Kess to the OBD2 port of my car (Skoda fabia 1.4 BBY) that has an ECU equal to the aforementioned and the results were the same.
– When I tested on my car do not use external charger (The voltage was a little below 12V)
Do you think the solution is to increase and stabilize the voltage through an external charger?
Is the correct voltage just as important for a reading?

2. Procedure with Magneti Marelli 4BV VW Gol 1.0 Engine: AZN
Tool used KTag using Boot-Mode

In this particular case I decided first to check that the control unit worked properly, for this mount the ECU in the bank, with its correct pin-out but without connecting the gray cable boot mode, and proceeded with a reading of the ECU supporting me in the Vag-Com. Then the vag com could read the ecu, see fault codes, etc.

Already the possibility that the ECU did not work was ruled out.

Then I removed it from the OBD2 adapter and made the connection as the Ktag indicated, connecting the gray cable in its correct boot mode, etc. (I am sure that all the connections were made correctly)
When I give it to read, it gives me the following error:

Communication error with the ECU: control all connections; if the problem persists, send log file to the assistance

In this case as a power source use the original transformer that brings the ktag that also does not reach 12v.

Could this also be the cause?
I can connect directly to the Ktag in the power outlet that he brings, a 13-14V source, or it is advisable to connect directly from the external source to the control unit without going through the Ktag.
Can the ktag break if instead of using the original transformer that he brings, I connect an external source of 13-14V, 2Amp?
I have doubts too, it is correct that when the ktag with its original transformer connected if the voltage is measured in the red wires (+) is 0, but when I read it the ecu in the ksuite if it gives the 12V. Is this operation normal?

Advice 1: Both occasions you say have low voltage, this can cause a lot of problems.

– you should always use a stabilized battery charger when reading / writing using kess
– for ktag go to maplins and buy a power supply, i use a tenma one, 5a 30v (both adjustable, i normally set at 14v 2.5a)

if kess identified the ecu (showing you SW/HW) but would not read then it shows you the tool is working, but telling you there is an error somewhere with these old Marelli ecu they will create you nightmare always! some work and some dont. i did a few of these a few years ago for grasstrack racing (especially the 1.0s) just to add a few extra hp for the drivers, some would read and some wouldn’t!

have you checked that these ecu are 100% compatible with tools? i know that some engine code read ok, some dont

ive never blocked an ecu when reading, but thats not to say that it ‘could’ happen. you should try a simple car like 2003-2008 vag both by obd and by bench, as if everything fail ecu is easy to replace preferably diesel rather than petrol too!

the world of naturally aspirated petrol tuning is not fun and not stress free, always.

Advice 2:

Try reading with a cheap mpps v18 if you cannot read with that then its not just kess n ktag

Advice 3: 

Fgtech manages to read, you need to open ecu take metal cover off eeprom(soic8)and bridge pins 4 and 5 with a wire. then you can read with fgtech via kline

VW Bora 1.6 2001 Magneti Marelli 4MV.

Pin 1-2 GND
Pin 3-4 12V
Pin 43 K-Line
Pin 60 Can H
Pin 58 Can L


I could read the Magneti Marelli 4MV and 4BV ECU, with Kess V2 using OBD. I also read a Bosch Med 7.5.10 with the Ktag. I think the success was in maintaining a stable voltage with a regulated source.
I am very happy with the reading.

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