A tricky intermittent failure on a Suburban SF-style RV furnace that would run normally for about 7 minutes before shutting down unexpectedly. After the shutdown, the furnace attempted to relight but failed repeatedly, creating a confusing symptom that could easily lead to misdiagnosis and unnecessary parts replacement.

In this guide, we break down the heat-induced gas valve failure that caused the problem, explain why the valve stopped operating once it reached temperature, and show the diagnostic steps used to confirm the issue. If you work on RV furnaces or troubleshoot intermittent heating problems, this walkthrough will help you avoid throwing parts at the system and focus on accurate testing instead.