ABS and brake warning lights turn on and off, could there be air in the ABS?

Hi,

If the system hasn't been opened, air shouldn't be an issue. Have you checked all wheel speed sensors?

Also, if you have a live data scanner, here is what I suggest. Watch the wheels' speed when moving. See if one of the wheels' speeds is different than the others. If it is, inspect that wheel speed sensor. If the sensor is sending an inaccurate signal, it won't set a code because the module doesn't realize it isn't sliding or skidding.

Take a look through this link, you may find it helpful:

https://www.2carpros.com/articles/7-common-symptoms-of-a-bad-automotive-abs-module

Let me know.

Joe