Jandy AquaPure Flow Sensor Failure: Codes 172, 175

What These Codes Mean

The flow/temp/salinity sensor is a combined unit installed in the 3rd port of the electrolytic cell. It monitors water flow, temperature, and salt concentration. Code 172 indicates the control board cannot communicate with the sensor properly, while code 175 specifically indicates an air lock condition or extremely low salinity at the sensor location.

The flow sensor is a backup safety device. The primary method of ensuring the cell only runs when the pump is on is the electrical interlock between the power center and the pump circuit. However, when the sensor reports no flow, the cell shuts off regardless of the electrical connection.

Step-by-Step Troubleshooting

Code 172 - Sensor Service

Check the sensor cable connection

1. Open the power center door. Locate the sensor cable connector on the Power Interface Board (PIB).
2. Verify the connector is fully seated. A loose connection is the most common cause of code 172.
3. Inspect the cable for damage, especially near the strain relief fitting where it enters the power center enclosure.
4. Turn power off and back on (cycle power). The unit must be power-cycled any time the sensor is disconnected or reconnected.

Clean the sensor

1. Remove the sensor from the 3-port cell by unscrewing the coupling nut.
2. Check for PVC glue, tape, or debris covering the sensor elements. These are common installation errors.
3. Clean the contacts with a mildly abrasive green fiber pad until bright and clean.
4. Rinse with clean tap water and reinstall.
5. Power cycle the unit after reinstalling. Wait up to 6 minutes for the "Wait" calibration to complete.

Verify sensor installation orientation

1. The sensor must be installed in one of the available ports on the 3-port cell, or upstream of the cell with no valves between the sensor and cell.
2. Refer to the manual's Figure 3 and Figure 11 for correct orientation.
3. If the sensor was installed incorrectly during initial setup, reposition it and power cycle.

Code 175 - Air Lock or Very Low Salinity

Bleed air from the system

1. Air trapped around the sensor can prevent accurate flow and salinity readings.
2. Open the air relief valve on the pool filter and run the pump until a steady stream of water (no air) comes out.
3. If the cell is mounted vertically with flow going down, air is more likely to become trapped. Check the orientation per Figure 3 in the manual.

Check salinity independently

1. Code 175 can also be triggered by extremely low salt. Use a Myron L meter or titration test to verify salt level independently.
2. If salt is very low (below 0.2 gpl per Level 2 code 182), add salt to achieve 3.0 gpl before troubleshooting the sensor further.

When to Replace the Sensor

• If the sensor cable is damaged and cannot be repaired.
• If code 172 persists after cleaning, verifying the connection, and power cycling.
• If the sensor produces erratic salinity readings despite being clean and properly installed.
• If a Level 2 code (180, 181, 183-186) is confirmed, indicating internal sensor component failure.