Interpretation of the message 'NE' on a Desjoyaux pH probe: Is it defective?

Client

I just tested my Desjoyaux pH probe and I got the message NE displayed. Does that mean my probe is defective?

Technical Advisor

Probably, please perform this test https://ph-redox-pool.com/gb/content/16-ma-sonde-ph-est-elle-hors-service-

Client

Thank you