______________________________________________________________________ Today our 6 yr old Trane XE80 (Model TUD060C936H3, with a White Rogers Model 50A50-473 control) did not ignite twice (blower comes on, igniter works although it may not actuate, not sure if natgas is flowing but it is available) — all other times everything works/cycles fine. For each time, I manually turned the furnace off (at the furnace) and, when I turned the unit back on, it reignited and continued to work OK. It’s been several hrs now of uninterrupted cycling. On one of the two occasions, I noticed the LED on the control unit flashed twice (which means “system lockout (no flame) check line polarity” per comments on the control unit). Thought it might be the flame sensor, but I downloaded the troubleshooting guide from the White Rogers website for Model 50A55 because it replaces the 50A50, but don’t know how much has changed. Most of the time, the furnace cycles fine, only on those two cycles today where the igniter (I assume) didn’t kick in or natgas did not flow. Don’t want us to be gone sometime and the furnace doesn’t kick in. Any thoughts? Since it’s Christmastime, don’t know whether to try and troubleshoot this myself or call in “an expert”. I’ve tried looking for troubleshooting info for the XE80 at Trane’s website and haven’t found anything yet. chuck Replies: chuck1127 “Re(1):Trane XE80 furnace – system lockout” , posted Mon 28 Mar 17:47 ______________________________________________________________________ Did you ever get a resolution to this problem? I am having the same issue and am looking for the problem without it costing me an arm and leg as the tech diagnosis. Thx-Chuck Thx-Chuck Xenos Webmaster “Re(1):Trane XE80 furnace – system lockout” , posted Sat 25 Dec 07:49 ______________________________________________________________________ If it is firing for a few seconds clean the flame sensor, if it not odds are it’s gas related, either a valve or regulator sticking. Xenos. The best way to escape a problem is to solve it.