M.T.H. Premier Bavarian Class 3/6 Express Operator's Manual page 26

There are a couple of ways to reset your MTH PS3.0-equipped engine:
Factory Resets – Clears everything – takes engine to just like it was
when you got it brand new
Feature Resets – There are a couple of Feature Resets that you can use
Lost or Unknown Engine Address and the 55-55-55 Address Reset
In some cases you may not remember or have somehow lost the engine address.
Following the above Feature or Factory Resets will allow you to recover an engine. The
limitation to this is that for most resets you must know the engine address. If you are
unsure of the engine address you can apply the 55-55-55 reset (send a value of 55 to
CV55 to engine address 55). In order for this to work correctly the engine's address
must NOT be 55. The engine will need to be sitting at some address other than 55.
Below is the method (55-55-55 Reset) you can employ to return an engine to its factory
default short address of 3 (it will also set the engine's long address back to its default –
usually 3333 or the cab number on some models) if you're unsure of the engine's
current address:
Check first to see if the engine happens to be sitting at address 55. Call up
engine 55 on your DCC handheld and hit F3 to start the engine up. If it starts up then
you can change the address to whatever you want using CV1 (short address) or CV17
and CV18 (long address)
If the engine doesn't start up at address 55 then you can use the 55-55-55
reset. To perform this follow the instructions below:
Premier Bavarian Class 3/6 Express Steam Locomotive
Send a decimal 08 to CV 8 to reset everything
entirely back to factory default
Send a decimal 192 to reset everything except user speed
tables
Press F28 twice (toggling on then off). This resets the
smoke, volume and lights back to their defaults
Send a decimal 64 for a Feature Reset. This resets
volumes, smoke and light settings.
Send a decimal 128 to reset only address values back to
factory default
Ensure the DCC system is powered up and power is on the rails
Call up engine address 55. NOTE – you are NOT changing the
engine's address to 55 you are just telling the DCC system to start
This is the same as writing 55 to CV55 to engine
address 55
Note: The engine address has to be something
other than address 55
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