Testo 320 problems

Dan C.

I've had a Testo 320 for about a year or two now. I really like it. Recently it stopped giving me a CO reading. When it does give me a reading it's very low. Most recently I did a test and the CO Reading was 9ppm. They then had mass save come out and do a combustion test for heat loan and the readings were over 100 ppm. I bought a new CO sensor and changed it. I went back to the same house today and I am now getting a reading of 0-1 ppm. Is there anything else I can do? Or do I have to send it back? The whole reason I bought this unit is because the sensors can be replaced and I thought I wouldn't have to send it back all the time to get calibrated.

Tim McElwain

Testo has a NOX eliminator which will give you much lower CO readings. Make sure you are using the COAF reading which will be the higher reading of the two CO readings.

Dan C.

They are both had zero sometimes air free is at one. But the strange thing is if I start my truck and check the exhaust it spikes the meter.

captainco

What was your O2 reading? Hard to tell if you have a leak or a weak pump without both readings. Take a match and hold it at the end of the probe for 1-2 seconds. The CO reading should be over 200ppm.