Heater keeps turning on and off every 5 seconds

Hello,
New user to pool and this forum. The pool and equipment has been well taken care of. I have the following
Pentair Easy Touch -4
Heater Pentair Heater 450
Pump Pentair Pump VF

I just bought the house and everything was working fine until I turned the temperature to 86 and since the the heater keeps shutting off and on after it reaches 81. It comes on for5 seconds, I hear the burner go on, warm water flows, and then it shuts off. After about 2 minutes, it turns on again.

I did some research here to try and troubleshoot and figured it was low RPM of the pump, but I have a VF pump so I tired increasing the GPM. Didn't work. Now the heater constantly restarts. Another thing I noticed in the pump status is the. "Filter Error" message. I haven't been able to locate what that means or how to fix it.

Thank you
Regards