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Pentair Pool Heater Error Codes: Complete MasterTemp Troubleshooting Guide

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.

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About These Pentair Poolheater Error Codes

Complete index of Pentair MasterTemp pool heater fault codes with direct links to each troubleshooting guide.

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

Error code displayed on LED panel
Heater shuts down mid-cycle
Heater will not ignite
SERVICE HEATER indicator illuminated
Heater runs briefly then locks out

Tools Required for Diagnosis

MultimeterPool pressure gaugeScrewdriver set

How to Identify Your Error Code

Note the exact code or indicator showing on the LED panel before

Note the exact code or indicator showing on the LED panel before doing anything else.

Access diagnostic history by holding Menu for 5 seconds in

Verify water is flowing through the heater by checking pump

Confirm gas supply

Perform a soft reset

Frequently Asked Questions

Where do Pentair MasterTemp error codes display?

Error codes show on the LED display panel on the front of the heater. On MasterTemp models the panel uses a 3-character display; on IntelliFlo-linked models the code may appear on the variable-speed pump display instead.

How do I access stored fault history on a MasterTemp?

Hold the Menu button for 5 seconds while the heater is in standby. The display will cycle through previously stored fault codes so you can see all recent errors, not just the most recent lockout.

What is the most common Pentair pool heater error code?

E05 and ERR PS (pressure switch faults) are the most common. Both indicate insufficient water flow through the heat exchanger, usually caused by a clogged filter, open bypass valve, or undersized pump.

Can I reset a Pentair pool heater fault code myself?

Yes. Press ON/OFF, wait 30 seconds, and press ON to soft-reset. For a hard reset, shut off gas and power for 60 seconds. However, the code will return if the underlying cause is not fixed.

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

Not always. SERVICE HEATER can be a simple annual maintenance reminder with no active fault, or it can illuminate alongside a real error code. Access the diagnostic history menu to determine whether a fault code is also stored.

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, MasterTemp 250, MasterTemp 300, MasterTemp 125

Last verified for technical accuracy on March 14, 2026