So-long story. There is 2004 Allroad 2.7tt with manual gearbox with low range. Vag com show me alot of dtc, but one of them was "checksumm incorrect". Owner just bought this car, and know nothing about it. I was very! surprised when i see an mtm-tuned motronic with UNDAMAGED mtm-seal (370 ps) and simple crypto-panel inside. As i know, this crypto can not be write from obd-plug, right?. So, i am downlowad this tuned file from motronic, and yes, there is "1 chk wrong". In mtm-file from sealed box. I do correction of checksumm, desolder crypto, install 29F800BB, upload corrected file. Still have "checksumm incorrect" dtc, that i can not erase with vag-com. Ok, i am upload absolutely trouble-free stock 551N file from auto-gearbox allroad. "checksumm incorrect" dtc again. So gurus, i need your help. How i can erase this DTC? maybe i need login procedure before erase? Or what? Or maybe motronic physycally damageg? Or only mtronic replacement will help?
And maybe anybody have ori-file for this manual gear-low range allroad? there no software version in this dump. I have another non-stock dump for allroad like this (low-range manual), and no software version too. 

Yes, code is stored in eeprom, like others, but i cant erase it. I dont think, that there is problem in eprom chk, i have problem with eprom chk in other car (due to owner attempts for immo disable), and in this case, even no communication with motronic and no start condition. And there in me7.1.1 eprom is 1kb 74hc00 (dont remember exactly), not 512b st95040, this is more difficult to fix...

No, galletto in boot mode on the bench. But there was incorrect checksumm in mtm file (and DTC about this) before i do anything with motronic. With this galeto i am reflesh some amount of me7.x.x without any problem.

Did you get this fixed already?
No immo adaptation needed.
Problem can be fixed by changing 3 bytes from flash.

The ECU checksum error is stored with a "01" at hex 1C and 2C in the 95040 EEPROM.
Both values must be "00" to clear the DTC.

If you have no access to your EEPROM you must desolder it.

If you have changed both values, you must recalculate the LoHi checksums at the end of both lines.
These are at hex 1E/1F for the value in 1C and 2E/2F for the value in 2C.

Ok, I have only seen a "01" with an ECU CS failure, and never a "33".

If the failure came back, there must be an other CS failure in your flashed software, or CS in your EEPROM is not right calculated after changing 1C and 2C to "00".

If definitely not, there must be a hardware failure in your ECU (flash, EEPROM or RAM).

Has you already tryed to flash a original stock software to flash and EEPROM?

These 6 DTC`s can bring a bad CS faiure.

P0601 - 16985 - Motorsteuergerät - Speicher Prüfsummenfehler
P0602 - 16986 - Motorsteuergerät - Programmierungsfehler
P0603 - 16987 - Motorsteuergerät - Fehler Dauerspeicher (KAM/EEPROM)
P0604 - 16988 - Motorsteuergerät - Fehler RAM-Speicher
P0605 - 16989 - Motorsteuergerät - Fehler ROM-Speicher
P0606 - 16990 - Motorsteuergeärt - Interner Fehler

I thought flashing through Nefmoto clears this

I've found that the Willem GQ 3X and Pomona test clip works great, even on a 7.1.1 with 5P8C03 rather than 95040.  No need to de-solder. 

http://www.mcumall.com/comersus/store/comersus_viewItem.asp?idProduct=4225