Oil Tank Gauge Stuck or Not Working? Here's How to Check It

Float gauges fail in boring, predictable ways: the float hinge gums up, the disc sticks at the top of the sight tube, or the indicator drifts. The symptom is a reading that never moves — which feels like a full tank right up until the burner stops.

The two-minute test: unscrew the sight-glass cap loosely and press the disc down gently with a finger (some designs let you lift the whole gauge slightly). If it springs back to a different level, it was stuck and the new level is roughly right. If it doesn't move at all, treat the gauge as dead.

The truth test is the stick. Measure liquid depth through the fill or gauge opening and convert with the right chart for your tank and orientation — the 275V and 330V charts cover most basements. If the stick and a sticky gauge disagree, believe the stick.

Replacement floats are inexpensive and DIY-able on most vented above-ground tanks, but if your tank predates you, have the tech who services the burner do it during the annual visit — and keep sticking the tank monthly in heating season regardless. Gauges estimate; the stick measures.