I run a small RV repair shop and spend a good part of my week chasing propane problems in travel trailers, fifth wheels, and older motorhomes that have seen a lot of miles. Most owners notice the system only when the stove will not light or the furnace starts acting strange, but the small leaks are the ones that worry me most because they can sit there for months. I have found them behind range fittings, under tank covers, inside cracked rubber pigtails, and once in a compartment that looked perfectly clean until I got my detector close to the regulator. Small leaks hide well.

Why the smallest leaks usually take the longest to find

People often expect a propane leak to announce itself with a strong smell the moment they open the entry door. Sometimes that happens, but a lot of the calls I get are much messier than that. A customer last spring told me they only caught a faint odor during cold mornings, and that detail mattered because temperature swings can change pressure and make a weak fitting show itself for a short window. By the afternoon, the smell was gone.

That is one reason I never trust a quick walkaround or a single sniff test near the tanks. On many rigs, the propane lines run through tight spaces, behind appliances, and under the floor where dust, road grime, and vibration all work together to loosen connections over time. I have seen a flare fitting hold for two seasons, then start leaking after a rough weekend on washboard roads because the line had been rubbing just enough to shift its angle. A leak can be tiny and still be serious.

Older RVs add another layer to it because the rubber parts age out before many owners realize it. Regulators, pigtails, and appliance connectors often look fine from three feet away, yet I can flex them by hand and see hairline cracking around the outer jacket. Ten years is a long time for parts that live outside in sun, rain, and freezing weather. I would rather replace a suspect hose early than explain later why a simple part became an expensive repair.

The tools and habits I trust during a real inspection

I still use soap solution, and I probably always will, because bubbles tell the truth when you can get your eyes directly on a fitting. But I do not rely on that alone anymore, especially in the packed compartments that modern RVs love to build around the propane system. A good electronic detector lets me work around regulators, manifold areas, furnace cabinets, and refrigerator access panels without taking half the coach apart first. That saves time, and it keeps me from missing the slow seep that only shows up when my probe sits in one place for several seconds.

For owners who want a useful place to compare detector styles before buying one, I sometimes point them to Wohnmobil-Propanleckdetektion because it gives a practical overview of the kind of gear people actually use around RVs. I still tell people to read that sort of resource with a mechanic’s eye and think about where they will be testing, not just what the product page promises. A detector that works fine on a bench can feel clumsy under a dinette seat where you are reaching past wiring, ducting, and a hot water line.

My routine is boring on purpose, and that is why it works. I check cylinder valves, pigtails, regulator vents, hard line unions, appliance shutoffs, and the final connection at each major propane appliance in the same order every time. On a standard travel trailer with two cylinders and four propane appliances, that can mean 20 or more spots worth checking before I decide the system is clean. Rushing is how you miss the leak tucked behind the range drawer or down by the water heater burner tube.

I also pay attention to what the leak detector is telling me over a full minute, not just the first chirp. Some sensors react fast to a concentrated pocket, while others give a more useful reading when I move slowly around a joint and let the air settle. If a compartment has poor ventilation, I will pause, let it clear, and test again from a slightly different angle because trapped gas can make the wrong fitting look guilty. That extra pass has saved me from replacing parts that were not actually leaking.

The trouble spots I see over and over on the same kinds of rigs

The most common failures in my bay are not dramatic blowouts or split metal lines. It is usually the simple stuff, like a regulator mounted where road spray beats on it, or a pigtail that has been twisted one too many times during tank swaps. I see this a lot on family trailers that get used hard from late spring through football season. The owners are not careless. The hardware just lives a rough life.

Slide-out kitchens and outdoor griddles have created a few more leak points than older layouts used to have. Every added quick-connect, every branch line, and every appliance valve is another place where vibration and weather can work on the system a little at a time. I worked on a fifth wheel not long ago where the smell only showed up after the owner ran the exterior cook station for about 15 minutes, and the culprit turned out to be a fitting that sealed cold but leaked slightly once heat built up around the line. That kind of problem can waste hours if you test with the system sitting idle.

Refrigerator and furnace compartments deserve more attention than they usually get. Both areas can collect dust, spider webs, rust flakes, and general grime that make a visual inspection harder, and they also tend to be places where owners do not look often unless an appliance stops working. I have found leaks where a burner assembly had been bumped during a prior repair, and I have found others where a hard line clip had broken loose and let the tubing vibrate against a sharp edge. Three missing screws can start a chain of trouble.

What I tell owners to do between shop visits

I do not expect most RV owners to become propane technicians, and I do not think they need to. What I do want is for them to slow down during setup and notice what the coach is telling them. If you open the tank valves and get a brief odor every single trip, that is not something to wave off as normal. The system should settle quietly.

I tell people to inspect the easy stuff every few outings, especially before a long trip. Look at the date and condition of the pigtails, make sure the regulator vent is not packed with debris, and pay attention to appliance behavior that changes for no clear reason. A stove flame that suddenly looks weak and uneven, a water heater that starts taking several tries to light, or a furnace that feels inconsistent can point to a leak or pressure problem upstream. Those symptoms matter more than people think.

I am cautious about telling owners to test every fitting themselves because there is a difference between being observant and getting in over your head. Still, a careful soap test on exposed connections near the cylinders can be useful if somebody understands the limits of what they are doing and turns things off the moment they see trouble. I would never call that a full inspection, because the hidden parts of the system are where many of the more annoying leaks live. A clean result at the front bottles does not clear the rest of the coach.

Most of my best service calls start with an owner giving me a plain, careful description instead of trying to diagnose it alone. They tell me the smell showed up after refilling the tanks, or only while the furnace was running, or only on cold mornings below 40 degrees. That sort of detail helps me decide where to begin, and it often cuts the job in half. Good notes beat guesswork.

I have worked on enough RVs to know propane systems reward patience and punish assumptions. If your coach smells off, acts off, or starts showing little changes you cannot explain, treat that as useful information instead of an annoyance to put off until next month. A half hour of methodical testing is cheap compared with scorched wiring, ruined appliances, or a trip that ends on the shoulder with the propane shut down. I would rather be the person who says the system looks good than the one explaining why a small leak got the chance to grow.