Two of the most common error codes on the Jandy AquaPure System are error code 172 and error code 186. Both codes indicate that the Jandy AquaPure Tri-Sensor needs to be replaced. When replacing your Fusion Soft System Tri-Sensor, we highly recommend the new style AquaPure Tri-Sensor R0452500 which has proven to be much more reliable than the older style sensors. Below we have listed the step-by-step instructions for the replacement. Note: the Jandy AquaPure Tri-Sensor is used in several Jandy salt water systems. This guide covers the replacement of the Jandy AquaPure Tri-Sensor in a Jandy Fusion Soft Nature 2 System integrated with an AquaLink RS Power Center.