Man...I need to get my eyes checked. Thanks for pointing that out!
Originally Posted by daleWV
I wondered the same thing. The service manual is not very clear. For example, C1900 is the trouble code for an unregistered TPMS sensor. Here's what it says about this code:
Originally Posted by Cobrajet
DTC C1900: Tire ID code No registration
DTC SET CONDITION
When the ID codes of the TPMS transmitter are not set in ETACS-ECU, and/or when ETACS-ECU is replaced with a new one, this code is set.
If the ID registration mode is terminated forcibly or timeout after one or more TPMS transmitters are registered in the ID registration mode, the ID codes in the ETACS-ECU are erased, and this diagnostic trouble code is set.
So the C1900 code is set if you have an unregistered sensor, but is that code being stored...or is it generated every time the car starts and the TPMS system goes through its self-test? Based on everyone's experience, it sure looks like this code will clear automatically once you install the registered sensors back on the car (like your flat tire example).
Based on what daleVW said above, maybe you can try triggering the sensors by dropping air pressure (without the triggering tool) to see what happens.