mastertemp 400

1. Heater turning off gas every 60 sec. HLS light was on. Checked the thermostat and it was trashed, wouldn't open. 2. Got a new thermostat, but it's not opening until water temp is 145F. OK note to self, don't use cheap knockoff themostat from Amazon. Will order another. 3. Shorted the HLS...

Guys, I need some help with a frustrating situation. My mastertemp 400 is 6 years old and always has worked great. Over the past year, the screen on the board would give out from time to time. Everything would work as normal but the screen was lit with no numbers showing up. When this...

Hi Folks, As a new poster but a user for many years I enjoy the site and all the great info. Recently I had my Temperature Regulator fail in my relatively new Mastertemp 400HD due to bad water balance and resulting corrosion. For reference I had an HLS fault that started the process with the...

two questions! I've scoured previous threads, but haven't seen this specific question. My heater will fire and run for 20-30 seconds SOMETIMES, and sometimes will run for several minutes at a time before failing with error E05 Through the many helpful posts in this forum, I learned to hold...

No error code or anything. Almost like it shows the temperature is 1 degree. It tries to start and then after a few attempts it shuts down and the red "service heater" light comes on .

We’ve encountered a very strange issue with our spa and neither we or our builder can figure out what’s wrong. 🤦🏻‍♀️ The spa will run fine during the day but sometime around 6pm (don’t know the exact time or if it’s even consistent) if you try to turn the spa on it will kick on for just over one...

Hi, I have read many post from this and other forums to try to fix my heater. I have had it since 2016 and it has been troublefree until rodents found it earlier in the year. I've tried to test a lot of things but I have run out of things to do so I hope that the details below may help provide...

This is the opposite of what everyone else normally asks about how to turn off the delay. I want to create a delay (the same as the pool cleaner delay) before the heater turns on in the intellitouch/screenlogic software. After 2 years of monitoring the heater behavior (Mastertemp 400) as we...

I've been scratching my head over this for a week now. I have 2 400k pool heaters for my pool. They both worked fine over the summer. Last year I had to replace the SFS sensor on one of them. The same one, a year later almost to the day, started acting up again. It starts heating, sometimes the...

Hello, I have my Pentair MasterTemp 400 connected to my Hayward Prologic board via the 2 wire method (18AWG per spec) Fireman Switch to the Heater1 relay on the Prologic I have enabled heater1 in the configuration menu on the ProLogic. I press heater1 and no light illuminates and it says Gas...

Hello, yesterday I started getting an E05 error on my Pentair master temp 400 HD. I opened the heater up and put a multimeter across the flue temperature sensor and I got 3.8 ohms. So I’m assuming that the temperature sensor is OK. The air intake is also fine and from what I can tell the water...

Hello Everyone, Some mice got into my water heater. They chewed up alot of wiring and I did a pretty good job patching it all up but I get no display on the control PCB. The system goes through a fenwal ignition system. The PCB does look like it has minor corrosion and no LEDs light up. Any help...

Hi all. I am having an issue with my pool heater and I saw similar issues in some old threads so thought I would post here. I had a pool guy change out my thermastor and then my control board in my Pentair Mastertemp 400 (about 6 years old) trying to resolve the my issue. Basically I could not...

Per the Mastertemp Installation instruction: ”The filter pump should run continuously when the heater is on, and for at least 5 minutes after the heater turns off. Any switches in the pump circuit (including circuit breakers) that can disconnect the pump must also disconnect the heater.” I...

I am having an issue with my Pentair Mastertemp 400 heater. When I turn on the spa or pool from my phone using Pentair ScreenLogic, or I turn it on manually from the Pentair Easytouch Control System, the heater takes a long time cycling through its startup process and then does not fire up the...

I have a mastertemp 400 HD heater and I'm having an issue with maintaining the temp. Initially when you turn it on, it stays on and heats it up well. However once it reaches the set temp, it will shut off Rapidly instead of staying on for a few minutes to heat it back up to a degree or two over...

Hi. Bought our house this past July. The heater - Mastertemp 400 - worked fine. We used it at least once per month through November. At one point - I think in August - Error 01 (Thermistor) was a problem. I replaced that, but later found the real problem was the connector on the control board...

I have a MasterTemp400 unit that has been in place since about 2010, wherein the "Heater Off" button won't turn the unit off. The button (and all other buttons) feel incredibly tactile and seem to be functioning. However the Heater Off button doesnt turn off the LCD display like it does in this...

I have a MasterTemp 400 that I have been troubleshooting since last year. I've check different foruns and looks like a common issue, but I have yet to see a resolution. Perhaps you can help. As soon as I turn the heat on, I see a 75 reading. It 'heat' blinks to call for heat and then steady...

Hi, My Pentair Mastertemp 400 goes through its electronic startup routine and then reports a HLS error (and service heater led). My water is circulating normally, my chlorine generator is saying that it is working but the heater stops as quickly as it starts without lighting or blowing. I...

I wanted to document this on the forum threads since this issue got diagnosed and solved via PM. First, let me give total credit to our esteemed forum expert @JamesW for helping me to diagnose, test and fix this heater issue. James' help saved me from calling in a "pool service" guy and...

Hello TFP experts. I have Mastertemp 400 that's about 5 years old. I have attempted a a deep dive search here and found a few threads that very similar. MasterTemp 400 Heater won't stay running, but it was never confirmed if a new control board solved the problem? Mastertemp 400 - Burner...

Hey experts, When I turn my mastertemp 400 onto spa mode. It will run for about a minute then turn on a HLS error light. After maybe two minutes light will go off and it will go through the same process again. This issue first started with an E05 error message. I came to this forum to start...