Digitron irratic readings

[Himark]

Im using a 2 window version and one cylinder started reading 16.18. 1900 2000 then dash line. Other cylinder fine, then shut off restarted both were reading 4.500 idling then one spikes 1900 then back 400. This a probe problem or gauge fubarred??

 

[mattymac]

I had a digitron do pretty much the same thing. It was a bad probe.

 

[Andreas83]

Try swapping over the connectors from the probes.
If problem moves to the other window, probe is faulty.
If problem is still in same window, guage is faulty.