Pentair Pool Heater Error Codes: Complete MasterTemp

Quick Answer

Pentair MasterTemp pool heaters display error codes like E05 (pressure switch open), ERR PS (pressure switch on IntelliFlo models), ERR IGN (ignition failure), ERR AFS (air flow switch fault), and SERVICE HEATER (maintenance reminder or active fault). Each code points to a specific subsystem failure.

Most Pentair MasterTemp issues I see in the field are the heater protecting itself from actual damage. These codes are basically a check engine light for your pool equipment. And honestly, nine times out of ten it's a flow problem or a gas hiccup, not a dead board or a fried sensor. Knowing the specific code tells you which subsystem triggered the lockout and whether you need to backwash your filter or call your gas company.

PentairPoolheater

About These Pentair Poolheater Error Codes

Seeing an error on your MasterTemp is almost always a safety lockout, not a death sentence for the unit. The control board's watching water pressure, air flow, and flame quality every single second it's running. Before you start ordering expensive sensors, check the basics. Your filter pressure and your gas valve position cause the vast majority of service calls I handle on these units. Seriously, I fixed four of them last week just by backwashing filters.

Most Common Error Codes

Low water flow through heater (E05 / ERR PS)40%

Ignition attempt failed after multiple retries (ERR IGN)24%

Combustion air flow switch did not close (ERR AFS)14%

No power to heater or tripped breaker (no display)12%

Annual maintenance interval reached (SERVICE HEATER)10%

Symptoms You May Notice

The LED panel on top is flashing E05, ERR PS, ERR IGN, ERR AFS, or SERVICE HEATER and the burner either won't start or cuts out mid-cycle.
Heater fires up, you hear the burner catch, runs fine for 5 or 10 minutes, then shuts itself down and throws a code on the display.
Burner just won't light. You hear the igniter clicking two or three times, then dead quiet. No flame, no lockout noise, nothing.
SERVICE HEATER light is lit solid and the heater won't run even though everything else looks normal when you check it.
Pool temp isn't climbing even though the heater seems to be running, and you only catch the fault code because you happen to glance at the panel mid-cycle.

Tools Required for Diagnosis

Phillips #2 screwdriverFlathead screwdriverDigital multimeter with continuity modePool filter pressure gaugeFlashlightManometer (for gas pressure testing if needed)Phone or camera to photograph fault codes before they clear

How to Identify Your Error Code

Frequently Asked Questions

Where do Pentair MasterTemp error codes display?

They show up on the small LED window right on top of the control panel. It's a three-character display showing something like E05 or ERR IGN. If your heater's wired into an IntelliTouch or EasyTouch automation system, that same code's probably showing on your indoor controller or in the Pentair Home app too, so you might actually know about the fault before you even walk out to the equipment pad. Which is pretty handy when it trips at 6 AM and you're still inside.

How do I access stored fault history on a MasterTemp?

Put the heater in standby, then hold the Menu button for about 5 full seconds. The display'll start scrolling through the most recent fault codes in order. This is the most underused feature on these heaters. A unit can trip a dozen times overnight, clear itself by morning, and look totally normal when you check it. But that stored history tells the real story of what happened, which is way more useful than chasing whatever single code happens to be showing right now. Use it every single time before you start swapping parts.

What is the most common Pentair pool heater error code?

E05 and ERR PS. Not even close. Both mean low water flow through the heat exchanger and nine times out of ten your filter just needs a backwash. I've driven to jobs expecting sensor replacements and it turned out to be cartridges that hadn't been cleaned in six months. Fifteen minutes of cleaning, code disappears, everybody's happy. If the filter's clean and you're still getting the code, then look at the pressure switch itself. About $35 for the part, usually not a bad DIY fix.

Can I reset a Pentair pool heater fault code myself?

Yeah, you can, but resetting without fixing the cause just buys you another 10 minutes before it trips again. Think of it like silencing a smoke alarm. The alarm being off doesn't mean there's no fire. Hit the ON/OFF button or cycle the breaker, let it fire back up, and watch it. If it runs fine the rest of the day, great. If it trips again on the same code within a few minutes, stop resetting and actually diagnose what the code is pointing at.

Is the SERVICE HEATER light the same as an error code?

Not exactly. SERVICE HEATER is kind of a catch-all indicator. Sometimes it's just the maintenance timer telling you it's been 12 months since the last tune-up, which clears after a service visit. But a lot of the time it's on because a specific sensor like the High Limit or the Stack Flue Sensor tripped and someone never pulled up the diagnostic history. Don't just reset it and assume it was the timer. Pull the fault history first and see what's actually hiding behind that light.

How much does fixing a Pentair MasterTemp error usually cost?

Depends completely on the code. E05 from a dirty filter? Nothing, just 20 minutes of backwashing. Pressure switch replacement is around $35 for the part, easy DIY. Igniter is $45 to $60. Gas valve is where it gets real, usually $150 to $250 for the part alone, and you want a certified gas tech doing that one. Control board is worst case, $300 to $500. But honestly, most of the calls I handle are flow issues that cost the homeowner basically nothing once they know what to look for.

Related Pentair Poolheater Error Codes

Code: SERVICE-HEATERPentair Service Heater Light Code: TROUBLESHOOTINGPentair Pool Heater Troubleshooting Guide Code: E05Pentair Pool Heater E05 Error Code Code: ERR PSPentair Pool Heater ERR PS Error Code: NO-POWERPentair Pool Heater Not Turning On Code: RESETHow to Reset a Pentair Pool Heater Code: ERR IGNPentair Pool Heater ERR IGN Error Code: ERR AFSPentair Pool Heater ERR AFS Error

Same Fix on Other Brands

Hayward poolheaterHayward Pool Heater Error Codes Guide

Models Known to Experience HUB Errors

This repair applies to most Pentair poolheaters with this error code. Common model numbers include:

MasterTemp 400 NG (460736), MasterTemp 400 LP (460737), MasterTemp 250 NG (460733), MasterTemp 250 LP (460734), MasterTemp 300 NG (461002), MasterTemp 125 (460765), MasterTemp 175 (460769), MasterTemp 400HDX (466000)

Written by

Raj Patel

HVAC & Water Systems Specialist · 15 years experience

Last verified for technical accuracy on March 14, 2026