Last updated: April 23, 2026
Furnace repair in San Diego County typically runs $200 to $900, starting with an $89 diagnostic that gets credited toward the fix. Ignitor and flame sensor problems make up most of the cheap end. A cracked heat exchanger is the one repair that usually means it's time to talk about replacement instead.
El Cajon hits some of the most extreme summer heat in the urbanized part of the county, 100 to 110 degrees isn't rare, which pushes every system toward larger cooling capacity. Bostonia and the El Cajon Boulevard corridor carry substantial rental-property stock, driving faster-turnaround work, while Fletcher Hills' upper-income homes run larger, higher-tier replacements. Permits route through the City of El Cajon, generally $250 to $450.
East County overnight freezes mean furnaces that sat idle through a hot summer often fail on the first genuinely cold morning, and that first-failure repair tends to be a full ignition-system job rather than a minor fix. Fall maintenance is the cheaper alternative that most homeowners skip.
| Item | Typical cost | Notes |
|---|---|---|
| $89 diagnostic visit | $89 | Credited toward the repair once you approve the work |
| Hot-surface ignitor replacement | $250 - $500 | The most common reason a furnace won’t light |
| Flame sensor cleaning or replacement | $150 - $350 | Causes the furnace to shut off seconds after igniting |
| Inducer motor replacement | $400 - $800 | Furnace hums or clicks but won’t start the burner cycle |
| Gas valve replacement | $400 - $900 | Safety component, always tested before replacement is approved |
| Control board replacement | $400 - $800 | More common on furnaces with electronic ignition and diagnostics |
| Blower motor replacement | $450 - $900 | Furnace heats but airflow through the vents is weak or silent |
| Heat exchanger replacement | $1,500 - $3,500 | A safety-critical repair, often the point to consider a new furnace instead |
Ranges reflect El Cajon and East County San Diego. Your exact figure depends on the factors below. We quote flat-rate before starting.
A furnace repair under roughly $500 on a unit less than 12 years old is almost always the right call. A cracked heat exchanger is different. It's a safety issue, not just a repair line item, because a cracked exchanger can leak combustion gases into the home. On a furnace old enough to need one, we usually recommend replacement over repair, and we explain exactly why before you spend money either way.
The $89 diagnostic gets credited toward the repair once you approve it. SDG&E and TECH Clean California rebates apply to new equipment, not repairs, so they come into play only if a repair turns into a replacement conversation, most often after a heat exchanger fails. We offer financing for larger repairs, and we'll tell you plainly when a repair isn't worth it anymore.
For a typical 1,400 to 2,200 square foot El Cajon home, expect $10,000 to $19,000 for a properly sized heat pump replacement. The key word is properly sized, El Cajon's 100-plus degree summer days mean an undersized system will run constantly and still lose ground on the hottest afternoons, so we size to actual peak load rather than assume the old tonnage was correct.
East County overnight freezes mean furnaces that sat idle through a hot summer often fail on the first genuinely cold morning, and that first-failure repair tends to be a full ignition-system job rather than a minor fix. Fall maintenance is the cheaper alternative that most homeowners skip.
$200 to $900 covers most repairs, including the $89 diagnostic that gets credited toward the fix. Ignitor and flame sensor issues run under $500. A gas valve, control board, or blower motor runs $400 to $900.
Usually yes if the repair is under $500 and the furnace is less than 12 years old. A cracked heat exchanger is the exception. That's a safety issue, and on an older furnace we typically recommend replacement instead.
A flame sensor cleaning or replacement is usually the least expensive fix, typically $150 to $350, and it's one of the most common reasons a furnace shuts off right after lighting.
A heat exchanger replacement runs $1,500 to $3,500 and is the most expensive single repair. Because of the safety issue involved and the age of furnaces that usually need one, we walk through the full replacement cost alongside it.
Flat-rate pricing, confirmed before any work starts. Same-day scheduling on most calls.