@akrogolf My best guess - If everything is working OK then I'd say that the error is due to the heater monitor command(s) - M143 of which you have two. But I don't think that you can assign multiple sensors to control a single heater - (which one would the firmware use if one read high and the other read low?). But for sure, you've only assigned one sensor to the heater in your M950 H1...T1. (I'm assuming that the semi colon before the "2" is to denote the start of your comment). So my best guess is that the second M143 using T2 is where it's falling over. Try commenting it out to see if the error goes away. If it does, then a work around might be to create a dummy heater - H2 using the same heaters but with T2 instead of T1. I have no idea if that would work but might be worth a shot.