D
Deleted member 143833
The calibration process measures the probe output at high and low points and expects there to be a minimum range between the 2 points; it is the readings - difference that determines the accuracy; yes, I'm over simplifying! You can have a probe that reads 'something' and still will not calibrate if the high and low calibration values are closer than tolerance woud allow; in other words the values read but the difference is so small between the points that the readings are inaccurate.
This all said; 1 bad calibration may not mean the probe is bad; it can also be that the calibration solution is bad. For example; if you calibrated with 2 solutions at the same value the calibration would fail so if the fluid was bad that would give a similar indication; the calibration would also fail. Since you mentioned you have 2 probes try 2 and verify it calibrates (that will somewhat test the fluid), then soak the other probe in vinegar for 1/2 hour, rinse blow off (dry) and try calibration. If it still doesn't work I'd then say you have a bad probe.
