Sta-rite heater manual - Sta Rite Sta-Rite Max-E-Therm High Effiency - Propane Heater - 333,000 BTU

SOURCE: Sta-Rite SR400 heater displays error E01 and doesn't fire.

Resolved - the thermister was bad.

SOURCE: sta-rite heater Display shows 125 degrees, won't activate heater

You probably have a bad sensor.  If you have a MAX-E Therm heater, then the part number is 42001-0053S.

SOURCE: Sta-rite propane heater turns on, blower on but it doesn't fire

There can be a couple of reasons for this issue to occur. The first thing to check is the dsplay panel for which Service light is coming on. If it is the Service System light, then there is not enough flow of water in the system. You may need to clean your filter.

If it is the Service Heater light, then the problem is with the heater. What you can do is restart the heater and watch the display panel. If the water temp display is too high, or low, then the issue is the Thermister and it will need to be replaced. If the temps are about the same, then try and start the heater. The same issue may happen again, but that is what you actually want to happen. Once this does, take off the top two halves of the heater and turn the display panel over. There are diagnostic lights on the backside of the panel.

If there is a red light next to one of the following: AGS, AFS,
SFS, HLS, PS or THERMISTOR, then that is the item causing the problem with the heater. If you need an Owner's Manual, there is one online at the following link:

http://www.inyopools.com/owners_manual/sta-rite_heaters_max-e-therm.pdf

SOURCE: sta-rite gas heater won't ignite

I am not sure if either of these issues have been solved, but with the AGS light on, you will need to check the flow of water first. If it is below what is needed for the heater, this will light up. If the water flow is fine, then check the water temp on the display panel. If it is readin higher than that of the ACTUAL pool water temp, you need to replace the Thermister.

If the water temp displayed is about that of the pool water, then the Automatic Gas Shutoff will be the next thing to check and replace.

You can tell IF a Sta-Rite heater has been converted by the model number. The Convesion Kit is supposed to come with a sticker stating that the heater has been converted, but there are two options for the kit and the one without the sticker is cheaper.

If you take off the top two halves of the heater, on the Junction Box there should be a Tri-fold card there. Unfold it, if the model number ends with NA it is a Natural Gas Heater, LP would be Propane.

SOURCE: sta rite 400na gives error code 05 after about 30 seconds

I am not sure if you have received an answer to the issue, or not, but just in case! An EO5 error code is an open stack flue sensor, or switch, There are two forms of the stack flue sensor, so you will need to know which one you have on the heater.

What this error code means is that the sensor "read" the flue temp to be over 500 degrees. Usually, it is just gone bad and reading the wrong temp.