For several months I've been trying to deal with a whiff of propane encountered under the reefer where the furnace resides.

First assessment was the smell originated from a dead mouse (caught in a trap in that space). But the odor persisted when the propane was activated. It was VERY slight, not even enough to trigger a portable sniffer.

At first, after confirming it was indeed propane and not dead rodents, I replaced the supply line to the reefer (I had already replaced it when installing the new reefer, but pinched the line - being too lazy to fetch the tubing bender from the shop - and it appeared I had created a pinhole). That failed to stop the leak.

I had a flare union that was suspect, in the furnace supply line. I replaced that, and still got the smell. All the joints, BTW, showed nothing on the bubble tests.

Today I removed the burner and the furnace solenoid valve and capped the propane supply line. NO SMELL! This means the culprit is the furnace solenoid valve; it would leak into the burner chamber, but would outflow to the furnace chamber, and from there, into the coach interior.

Somewhere I heard, "It's always SOMETHING!"

The new valve is installed, and the leak seems to have stopped (no odor after an hour, where before, it was present after 15 minutes).

From pplmotorhomes.com (usually best price): $179
americanrvcompany.com: $122
Local RV dealer: $115

Funny how dead rodent and propane can smell so similar at times.

I was working a Hippi Festival a few years back and a guy told me there was a dead mouse in the "camper" he had rented.

I asked if I could take-a-look.

Sure-enough, one of the burners on the stove was cracked-open just a little and the pilot had not been lit.

...no more "dead mouse"...