Pentair Mastertemp 400 Stack Flue Sensor Immediate Shut down

[km1222]

Hello,

I have a five year old Mastertemp 400 Pool/Spa heater setup that was getting E06 error (first error ever with heater).
THEN:
Replaced Sensor with aftermarket, and cleared the E06 code, but heater would shut off with SFS code on back of control board after 1-2 minute run.
I ohm tested prior to and post install at 3.8Mohm. Wires running to control board at 3ohm.
Tested flue gas with meat thermometer and it was rising, but never got over 250 when running in those 1-2 minute spans.

NOW:
Getting E06 code before ignition. Air blower turns on, 20-30 seconds later, either while gas valve clicks, or about when it should, the heater goes into SFS error prior to ignition.
I have not tested Thermal Regulator, or Internal bypass.

I do not understand why the SFS sensor would be triggered prior to startup.
Breaker has been cycled multiple times, but the only thought I have is that the control board needs to be reset with the 10 second hold on membrane pad "OFF" button,,etc.
Without tearing into the manifold yet, is there anything else I am missing?

Thanks,

 

[ajw22]

If the heater throws an SFS error before the blower runs and the heater starts, the Stack Flue Sensor is bad. Stack Flue Sensors on fairly new heaters are being reported as failing.

Get another SFS.