Almost never on its own. The pattern of reductions tells you far more than the fact of one, and what it tells you is about the seller.
The most common reason is the least dramatic: the home was listed above what buyers would pay, and the seller has now accepted that. It is the correction of an opinion, not a disclosure about the property. Reductions happen constantly, and most of the homes they happen to are entirely fine.
A reduction tells you about the seller's expectations. It tells you almost nothing about the furnace.
Treat it as a prompt to ask questions rather than as a discount already granted. Two worth asking through your REALTOR®: what the full listing history looks like — previous listings, previous prices, whether a relist reset the visible count — and whether offers have come and gone.
Then resist the obvious mistake. Buyers assume a reduced home has more room left in it. Sometimes a reduction has moved a price from unrealistic to correct, and correct is the price you now have to beat someone else to. How much to offer below asking →