Pentair Pool Heater Error Code 19: How to Fix It

Q: What does Error Code 19 mean on a Pentair pool heater?

Error Code 19 on a Pentair pool heater indicates a fault with the air temperature sensor (also called an ambient air thermistor). This sensor monitors the air temperature around the heater, and when it reads an out-of-range value or loses continuity, the heater shuts down and displays code 19 to prevent damage.

Q: Can I run my pool heater with a code 19 fault?

No. When Error Code 19 is active, the Pentair heater will lock out and refuse to fire. This is a safety protection feature. Attempting to bypass it is not recommended, as the air temperature sensor helps the heater operate safely and efficiently. You should resolve the fault before running the heater.

Q: How much does it cost to replace a Pentair pool heater air temperature sensor?

The air temperature sensor (thermistor) itself is a relatively inexpensive part, typically costing between $15 and $50 depending on the model. If you hire a pool technician, expect to pay an additional $75–$150 in labor, bringing the total repair to roughly $100–$200 in most cases.

Q: Why does my Pentair heater keep showing error 19 after I replaced the sensor?

If Error Code 19 returns after replacing the sensor, check that the new sensor is the correct part for your specific heater model. Also inspect the wiring harness and connector on the control board for corrosion, bent pins, or damage. In some cases, a damaged control board connection can mimic a sensor fault even with a good new sensor installed.

Q: How do I find the right replacement air sensor for my Pentair heater model?

Locate your heater's model and serial number on the rating label, usually found on the inside of the front panel or on the back of the unit. Use this model number to search Pentair's official parts lookup tool or provide it to a pool supply retailer to ensure you get the correct thermistor sensor for your specific unit.

Abstract

Pentair pool heater Error Code 19 indicates a fault with the air temperature sensor, which monitors the ambient air around the heater to ensure safe and efficient operation. When this sensor fails, reads out of range, or loses its connection, the heater will lock out and display code 19 to protect the unit. In many cases this is caused by a damaged sensor, a loose wiring connection, or corrosion — all of which are diagnosable and often fixable at home.