RV LP Gas System Troubleshooting Guide

—  Empty or near-empty tank — check the gauge first, it’s the most common cause
—  Tank valve not fully open, or a closed shutoff valve somewhere in the line
—  The excess-flow safety in the cylinder valve or QCC1/Type 1 connection has locked out after the tank valve was opened too fast (often wrongly called “regulator bypass mode”). Reset: close all appliance valves, close the tank valve, wait about a minute, then open the tank valve slowly. The OPD on the cylinder is a separate overfill device and doesn’t cause this
—  Air in the line after a tank change or after running fully empty — may take several ignition attempts to purge
—  A clogged orifice or failed igniter/thermocouple at the specific appliance
—  Low house battery voltage — DSI (direct spark ignition) furnaces and water heaters run on 12V DC for the ignition board even though the appliance burns propane; a weak battery produces a spark too weak to reliably ignite the burner

—  Yellow/orange flame usually means a dirty burner orifice or insufficient combustion air
—  Weak or low flame across all appliances suggests a regulator or supply pressure issue
—  Soot buildup on cookware or nearby surfaces means incomplete combustion — have it inspected before continued use

—  Detectors have a service life of roughly 5 years from date of manufacture — check the manufacture date before assuming a leak; the internal sensor degrades with age regardless of use
—  Cleaning products, aerosols, and even some perfumes can trigger false alarms
—  Look for UL 1484 (LP gas) and UL 2034/CSA 6.19 (CO) certification on any replacement unit — combination detectors are engineered with correct dual-sensor placement (LP low, CO at breathing height), so don’t relocate one sensor without the other
—  A genuine alarm with no identifiable trigger should always be treated as real until proven otherwise — shut off supply and have the system leak-tested

—  Changeover indicator shows red/empty on a full tank — usually caused by opening the cylinder valve too fast; close it, disconnect and reconnect the fitting, then reopen slowly
—  Weak flame at appliances despite a full tank — check the regulator vent for ice, insect nests, or paint blocking it, which restricts the diaphragm
—  Two-stage regulators should be inspected annually and replaced roughly every 5 years even without symptoms — the internal diaphragm degrades regardless of use
—  A soap-bubble test on every fitting is a safe DIY leak check — bubbling means a leak, no exceptions
—  Never use an open flame to check for a leak

—  DOT cylinders (portable, vertical, removable — typical on trailers) require recertification every 12 years from manufacture, stamped on the collar
—  ASME tanks (permanently mounted, horizontal — typical on motorhomes) are filled in place with no DOT-style recertification interval, but need periodic visual inspection
—  Since 2002, all DOT cylinders up to 40 lbs. require an OPD overfill prevention valve (triangular handwheel) — fill stations won’t fill a cylinder without one
—  Propane is always filled to 80% of capacity, never 100% — that headspace allows for liquid expansion as ambient temperature rises
—  Never store or transport cylinders inside the coach — propane is heavier than air and pools at floor level in an enclosed space if it leaks

Any smell of gas, a soap-bubble test that shows a leak, a regulator that won’t reset, or repeated detector alarms all warrant a full leak-down test and system inspection. This is one system where guessing costs more than a diagnosis — both in dollars and in risk.