Turn on the Pentair heater and it flashes code 128 and R=8. It runs but turns on and off every 1 minute eventually gets to temp but takes 3 tims as long. Is this a generic code ?? thanks for your help

check gas pressure possibly running out of gas

A dirty filter can cause low pressure and as a result, cause the heater's pressure switch to turn OFF. A dirty filter can prevent a heater from firing and it can also cause your heater to shut off before warming the water to the desired temperature.
https://www.inyopools.com/Blog/the-most-common-pool-heater-problems/
troubleshoot
https://www.youtube.com/watch?v=V8lbH-zVQ2k

My EasyTouch was set to "Man. Heat>ON". Once I turned that off, it worked from ScreenLogic.

This is not an error code. 128 r13 is the normal programming or software version for your model. you need to press the spa on button again, make sure the temp set point is higher then the actual water temperature

If all else fails call 800-831-7133
http://www.pentairpool.com/pdfs/MasterTempOM.pdf

128 r13 is not an error code. its the startup sequence of that heater

Most of the time I have found the problem to be the thermistor. It is located on the water manifold of the heater. Usually the panel lights, flashes then to 888 and back to dashed lines. SW light is green, and service light is red. It costs 25 to 45 dollars, and takes 5 minutes to repair. New thermistor looks identical to old so replacing it is very easy.
thanks please let me know if this was helpful