How To Replace an AutoPilot Tri-Sensor


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The Tri-Sensor (APA0003) for the AutoPilot salt chlorinator will occasionally fail. When the Tri-Sensor fails the chlorinator will stop generating chlorine. The following steps will provide a guide on how to replace the APA0003.

Things You'll Need

Step by Step


Step 1

TURN OFF THE POWER TO THE TIMER BOX. There should be a circuit breaker before the timer box where the power can be turned off. This is important because you do not want the pump running when you remove the existing sensor.

Step 2

Open the air relief valve located on top of the pool filter. This will release the pressure from the system and make it easier to remove the Tri-Sensor.

Step 3

Disconnect the AutoPilot Tri-Sensor from the power center. Press the two white tabs inward to remove the cable plug.

Step 4

With a phillips head screwdriver, remove the two screws retaining the Tri-Sensor in the tee joint of the manifold.

Step 5

Note the direction of the flow tab. The flow tab should be pointing in the same direction as the flow arrows on the manifold.The Tri-Sensor must be installed in the same orientation when it is replaced.

Step 6

The AutoPilot Tri-Sensor can now be pulled out of the tee. Firmly grip the Tri-Sensor assembly with a large pair of channel locks or strap wrench. Twist the Tri-Sensor back-and-forth while simultaneously pulling the Tri-Sensor straight out of the tee joint.

Step 7

Line up the new AutoPilot Tri-Sensor (APA0003) on the tee. Make sure the flow tab is pointing in the direction of the flow.

Step 8

Press the Tri-Sensor into the tee and make sure the holes from the sensor match up with the holes on the tee.

Step 9

Tighten the two screws and secure the Tri-Sensor to the tee.

Step 10

Plug the Tri-Sensor (APA0003) cable back into the receptacle on the power center.

Step 11

Turn on the power at the circuit breaker.

Step 12

Any air in the piping should be coming out of the open relief valve. When water starts to spray out of the relief valve, shut the valve off.

Step 13

After a couple minutes the AutoPilot control box should display the output level, time, and temperature.


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 Posted: 5/1/2018 

Per AutoPilot - The Tri-Sensor does not have the pilot holes, although the Manifold has them. The customer can use them to drive the screws in using a screw-gun (drill). All the customer needs to do is make sure that the Tri-sensor is pushed all the way into the Manifold.

Anonymous  Posted: 4/27/2018 

My replacement unit has no pilot holes either. Should I drill? It did come with replacement screws so it seems they should be used, just no pre-drilled holes.

Anonymous  Posted: 5/17/2017 

I have purchased several things from you, but not the Autopilot. I have a brand new sensor that has no holes either. I will drill pilot holes before installing. Thanks for offering to help me out.

InyoPools Product Specialist  Posted: 5/14/2017 

Anonymous (Tri-Sensor) - If you bought the unit from us, give one of our service reps a call at 877-372-6038. They will look into getting this unit replaced.

Anonymous  Posted: 5/11/2017 

There are no holes in the factory installed sensor. I have one now to replace and the screws were just driven into the sensor at the factory resulting in cracks and now leaks.

InyoPools Product Specialist  Posted: 3/26/2016 

AutoPilot Tri-Sensor - There should be a set of holes in both the sensor and the tee. See Step seven of this guide. If not, I would get an exchange from where you purchased this sensor. I would not drive a screw into the sensor without a starter hole. You might split or weaken the sensor.

Anonymous  Posted: 3/24/2016 

There are no screw holes to line up with in the sensor body. How far should you push the new sensor into the tee. Everything worked as it should. Dont forget to lub the "O" ring.

 Posted: 6/13/2013 

perfect step by step, although I don't have the air release valve. Otherwise nice job!!!