Decoding RS232 on the scope and fixing a Temtop M2000C that's stuck on "Sensor preheating" 

Thank you! Glad there are still guys like you who try to investigate and fix rather than throw in the trash and buy a new one.

Thank you for your efforts and video. It was so helpful. I like you liked the instrument but was ready to order another one since the CO2 meter would not go by the preheating function and give me a reading. I think I will be able to fix my device. Thanks again.

Ha! Thanks! Mine was stuck on preheating, thought it was perhaps the battery, so plugged it in to charge. Saw it added a COM port. Started googling for if anything supports that protocol and low and behold, your video with the fix.

Great look into it and thank you. Just took mine apart and ordered a battery.

Great video. Turned mine on today and the sensor was stuck on preheating. The date on the back of the unit is 3.23.20 - so about 3 years old. I will be replacing the battery. Thanks for saving me some money :). Update: Well I installed a new battery, tested it and it worked. Set the date and time and took it outside to calibrate and it still worked when I brought it back in. Put the back cover back on and it was back to permanent pre-heating. Opened it back up and put in another new battery and it still would not work. Not sure what went wrong. I was pretty careful, but oh well. I just received my well-rated new standalone detector with long-lasting (supposedly) replaceable batteries. I still enjoyed your video and was happy your solution worked even if success was short lived.

Thanks for the instructions!

Saved my Temtop m2000! Thanks

Thank you for the Help ! Great video

This was a huge help, thank you. Saw your Amazon review and loved the deep dive you did on this video. Replaced my battery and problem fixed! I would not have figured that one out. Much appreciated! Well done

thank you, this video saved me money! thanks again!

Thank you! This was extremely helpful!

Thanks! Do you have any idea if the advertised 3 year lifespan is just because of that battery or either of the sensors actually degrade over time?

Thank you so much! My meter died over a year ago, but it looks like I will finally be able to bring it back. Speaking of the unit, is it just me, or is the formaldehyde sensor attached shockingly bad? Mine appears to be just flapping in the wind on two blobs of solder and possibly tearing the traces on the PCB. I even needed to bend it out of the way to get to a screw. Some hot glue will be applied soon.

Thank you!!!!!

Problemd fixed because of your video, thanks so much!

Saw the Amazon review, great video. Any idea on the calibration functionality? I wasn't sure if this would calibrate to 0 or to some other known value.