Pentair Max-E-Therm Troubleshooting Guide
The Pentair Max-E-Therm is a high-performance gas pool heater known for its efficiency and reliability. When issues occur, the heater displays error codes on the LCD panel to help diagnose problems.
This guide covers all Max-E-Therm error codes and provides troubleshooting steps for pool service professionals.
Understanding the Control Panel
The Max-E-Therm features an LCD control panel that displays:
- Current water temperature
- Set point temperature
- Operating mode (Pool/Spa)
- Error codes when faults occur
The diagnostic LED flashes to indicate fault conditions:
| LED Pattern | Condition |
|---|---|
| ON (solid) | Control Fault |
| 1 Flash | Air Flow Fault |
Max-E-Therm Error Codes
ERR PS - Water Pressure Switch
The water pressure switch is open, indicating no water flow through the heater.
Auto-clear: Yes - clears when water flow is established
View detailed ERR PS troubleshooting
ERR HLS - High Limit Switch
The high temperature limit switch is open. Water temperature after first pass through heat exchanger exceeds 135F.
Auto-clear: Yes - clears when temperature falls below 135F
View detailed ERR HLS troubleshooting
ERR AFS - Air Flow Switch
The air flow switch is open. The blower is not running or airflow is restricted.
Auto-clear: Within 60 seconds if adequate airflow established
View detailed ERR AFS troubleshooting
ERR IGN - Ignition Failure
The ignition control module was unable to ignite the heater.
To clear: Press HEATER OFF button
View detailed ERR IGN troubleshooting
ERR AGS - Automatic Gas Shutoff
Water temperature after second pass through heat exchanger exceeds 140F. Front panel buttons are disabled.
To clear: Cycle power to heater
View detailed ERR AGS troubleshooting
ERR SFS - Stack Flue Sensor
Stack flue temperature exceeds 480F. Front panel buttons are disabled.
To clear: Cycle power to heater
View detailed ERR SFS troubleshooting
E01 - Open Water Temperature Sensor
The water temperature sensor circuit is open.
To clear: Press HEATER OFF button
E05 - Open Stack Flue Sensor
The stack flue sensor circuit is open.
E06 - Shorted Stack Flue Sensor
The stack flue sensor circuit is shorted. Front panel buttons are disabled.
To clear: Cycle power to heater
126 - Shorted Water Temperature Sensor
The water temperature sensor circuit is shorted.
Initial Troubleshooting Steps
Before diagnosing specific error codes:
- Verify pump is running correctly
- Check that there are no blockages in the system
- Confirm valves are correctly positioned
- Verify time clock is set correctly and running
- Check voltage matches heater configuration (120V or 240V)
Voltage Configuration
IMPORTANT: The Max-E-Therm operates on either 120V or 240V AC.
- Black plug: 120V configuration
- Red plug: 240V configuration
WARNING: Installing the wrong plug will damage the transformer, control board, and ignition module, voiding the warranty.