Time will tell about the 'fake' TB1 code.
"Unless you have the appropriate diagnostic gear to reset all the engine ecu learned values and adaptations after removing the box then yes they are detectable. The internal document you refer to is 100% kosher, I've seen it direct from elsapro on the official TPI listings. Whether they decide to deny a warranty claim is down to the individual/dealership looking at the car."
" The technical documentation with all the answers you're looking for is hours and hours.. and hours of reading. I couldn't tell you what the factory scan tool is looking for on every engine/ecu type. The one test that sticks in my mind was for the C7 RS6 which gave a tolerance for the variable cam timing learned values as a way to check for modifications."
"Modern VAG cars have two flash 'counters'. The 1st is partially accessible by tuners and tuning companies which can block ECU changes etc, but the 2nd is completely inaccessible/encrypted and increments at every use of an external device which alters/changes the state of the ECU.
A VW dealership doesn't search for flags, they only look via ELSA for existing registered flags. Here in the UK, VW AG ask all dealers to run a specific diagnostic report (called SVM) which gets uploaded to the VW AG servers via VAS online. An automated response will be received. and if a flag has been found that flag will be shown and registered to the database. The diagnostic tool has no capability to do this locally. No information about a cars tuning state is held on the car's ROM, it's held centrally at VAG. VW keeps that record centrally of what the count number should be for each VIN (based on how many times it's been plugged into their systems), if the count displayed sits outside the number expected, then it goes into the first flash counter and looks for the TB1 and TD1 errors. It is when these are flagged, warranties are usually rendered void, and as previously mentioned this is a big thing in current VAG climate where every penny counts.
As mentioned, the flash counters serve two different purposes, one counts, one analyses. There is also another bit of the algorithm that analyses 'hardware' modification (tuning boxes and unidentified hardware that’s been plugged into the ECU) which produces a TXD code that is then monitored in the detection algorithm. It’s simple maths which will then flags the appropriate error (TD1, TG1, TE1 and TB1)."
