Parkside PPHM 14 A1 Operation And Safety Notes page 31

If necessary, repeat all preceding steps of this section to
manually calibrate one or both of the other pH values.
Once all manual calibrations have been completed
and passed, the product is ready to measure the
pH value of liquids (see "Taking a measurement").
Fail: Err is flashing in the display 6 after manual
calibration: The manual calibration has failed.
Remove the product from the pH buffer solution.
Clear calibrated data from the internal memory of the
product (see "Clearing calibrated data from product").
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