Subject codes are indicated on the PureLink display. I know 125 is "cell needs to be cleaned or replaced". It is clean, so not looking good. The cell is out of warranty, installed about 2 1/2 years ago.
I can't find a code 154 for this equipment. I have a troubleshooting guide with voltages for the various test points, etc. but it is not for the PureLink model that I have. Maybe for an earlier model. I have Flow (per the display) and when the cell is On, the voltage at the cell is 37 VDC (measured by pulling back the power cable just enough to check with volt meter). The sensor went flaky last year and was replaced under warranty.
What else can I do to confirm the problem is the cell before purchasing a new one? Not sure where to verify the exact model number PureLink that I have or where to find the appropriate troubleshooting guide.