698 Fault Analysis/Trouble-shooting8.6 Warnings - Causes and SolutionsIn general: Warnings do not affect the measurement functions.8.6.1 LT2-K Calibration MenuThis message is output if the AC internal resistance (R I) of the ZrO2 cell exceeds the permis-sible limit of 200 during operation.Possible cause:Probe aged (worn out) Obtain a spare probe and replace.Measurement can continue, using caution. Check accuracy by counter-measurement,see chapter 6 Operation– Check fuses F2, see chapter10.6 Fuses– Fault in supply section electronics replaceCheck the Lambda Transmitter’s electronic:Measure the AC voltage across LT2 terminals 33 and 34, using a multimeter.The result in mV corresponds approx. to half the AC internal resistance.8.6.2 Offset Voltage out of rangeDuring offset calibration an invalid voltage is detected.Check if the measuring cell has been supplied with air.• Check if the flow of compressed air/instrument air is sufficient.If the rise of pressure is higher than 1 ... 2 mbar, see chapter 7.1.1 Calibrating the Air Volt-age (Offset)• Check if pre-filter is torn?If OK check probe voltage in air.Permissible range: +5 … -30 mV.Reversed polarity of the probe terminals 33/348.6.3 Reference Air Is Missing (Indication as a Warning in Parameter 395)Select in parameter 395 sets if the indication should be a fault or a warning (default = failure).
