Pentair Master Temp 250 E01

[mikeboyle]

I have a MT 250 running the heat on the hot tub in the gym I work for and I keep getting a random E01 code and the heater shuts down. I have been able to determine that E01 is referring to a temp sensor error, but can not find any information on how to actually diagnose the problem. The heater will reset and work fine for random periods of time but will eventually set the E01 code and shut down. I don't want to throw parts at it without determining the actual issue first. Is there any info on how to test the sensor and/or a diagnostic chart to follow in order to test the circuit? I have the owners manual and it doesn't have anything in it about the code. Thanks in advance for the help and thanks to everyone in here that has posted in the past. I have been able to diagnose all the other problems and answer any questions I've had to this point just by searching.

 

[mikeboyle]

A little more info if it helps to point me in the right direction. I reset the heater on Sunday night when I serviced the hot tub and it has run without shutting down since. Watching the control panel when the heater kicks on the yellow heat led will flash for a few seconds and then turn solid until the unit cycles. Randomly the heat led will flash for a few seconds then the service heater led will come on. When it is on the PS (Pressure Switch) led will come on. This typically only lasts for 10-20 seconds before the service heater and PS led's go out and the heater led starts flashing again. The unit has maintained the set temp all week so far.
If is matters, the PS switch was replaced last fall and has worked fine up till now. Our sister gym was having all kinds of different issues with their heater and it was determined that the pressure regulator for the incoming gas had never been adjusted (was way too high). I don't know if this is my issue as well, but I have an appointment with a tech to have it tested and adjusted if necessary. If anyone has any thoughts I'd appreciate any feedback.

 

[mikeboyle]

Figured I'd update this with what I found incase someone else has a similar issue. The problem turned out to be the temperature sensor. When operating the digital readout would always sit at 102*F (set for 103*). I noticed the heater was cycling on and off more frequently than normal so I started testing the water temp manually. With a reading of 102* on the digital readout, actual water temps were as high as 107* and low as 97*. Change out the temperature sensor and all seems to be working fine.