20 Most Recent Pentair Mastertemp Pool & Spa Heater Dual Electronic Ignition 400,000 Btu Lonox Propane 460737 Questions & Answers

I have the same exact problem with this unit. Obviously getting gas to the unit, because it runs and pumps out some serious heat for a short time, but then kicks off. Did anyone ever figure this out or did you buy a new heater? :-)

This could be a number of things. Most often it will be the internal by-pass. You find the assembly inside the water header, it controls water flow through the heater. When it goes bad it can open at a low temp and keep the water from going through the heater.
Also you will want to check the temp probe on the side of the header. If this is bad it will usually show up on the temp display though.

E05 and E06 is the error codes for a faulty stack flue sensor. try changing the sensor first is the cheapest. if that doesn't work check for corrosion on control board in which case will have to change out board.

Hello.... HLS usually means hi limits.... check the connectors at the high limit switches, to make sure they're not rusting off. If they're good, and the heater fires, but turns off after a minute or two, the problem lies usually with the temperature regulator.... it's the round cover with the 4 slits in it between the inlet and outlet. It comes out counter clockwise. It holds a spring with what would be a car thermostat attached to the end of the spring. That thermostat can be malfunctioning, and it will allow the water to get too hot coming out of the heater, which trips the hi limit. A quick fix is to remove the spring with the temperature regulator, and put the cap back in place. You definitely want to get another one to replace it, because the efficiency rating of the heater will go down considerably.... but it will do the job in the meantime with no danger. (Its like running a car with the thermostat removed, it can be done, but the engine runs too cool). They cost about 50 bucks on amazon.

Number one sounds like a board issue or if the pool is on automation the temp sensor. Number two sounds like the thermo regulator which is located in the inlet/outlet headers. If you need further help, reach me via phone at https://www.6ya.com/expert/keith_d879ea386fed3a1a

check the fuse inside the control box

Could be the temp sensor about 50-60 bucks, the book will say the board about 350-500 bucks. Try the temp sensor first. If it's reading over what the water is then that is probally the problem.

This issueis related to the stack flue sensor and it might have a wiring problem or a bad sensor. I recommend you call the Pentair technical support at 800-693-0971and they should be able to help you figure this issue out further. Ihope this helps.