In all my years (ha ha), front boards are what i have replaced the least of on these units. I know this will sound a bit unorthodox but it may just be the tri sensor. When Jandy had trouble with them some years back, they were causing all sorts of codes unrelated to the 172, 186 which were actually related to the tri sensor. You can do a test on the tri sensor that is pretty easy. Remove the sensor and put your thumb on any of the three sensors (little shiny disks) It doesn't matter which one as you will do this for all three. Now slide your thumb off the disk, and if you can feel a ridge between the disk and the epoxy it is set in, that is evidence that the disk has receded, and has probably let water in behind the sensor, and caused it to fail. If your sensor is made with white epoxy, there's a good chance that it has failed. The new ones are now made with black epoxy, and are equipped with a small "daughter" board that calibrates (fools) the front board, and allows more stable operation. The sensors i believe aren't too expensive when purchased on-line.
Manufacturer claims cell life to be around 5 years (10,000 hrs.). So if you are close to that, you may want to consider a new unit. That unit is still available, but the cell is redesigned, and requires a bit of re-plumbing. However the box should be plug and play.
