Generator Fault Codes by Brand

Plain-language explanations of what your standby or portable generator's fault code, blink pattern, or warning display actually means — what commonly causes it, what's safe to check yourself, and when it's a job for a licensed technician.

Look up a code directly

Know the code already? The code lookup searches every code on this site by number, brand, or keyword and links straight to the page that explains it. Curious what a repair actually runs? Jump to what generator repairs cost.

Start with what your generator is doing

No code visible yet, or the display is blank? Start from the symptom.

• Generator Won't Start
• Generator Runs But Won't Transfer Power
• Overspeed Shutdown
• Low Battery or Charger Fault
• Generator Runs Then Shuts Down
• Exercise Cycle Failure
• Low Oil Pressure Shutdown
• Overload or Nuisance Tripping

Start with your manufacturer

• Generac Guardian/Protector fault codes — 10 codes (Evolution/Nexus controller)
• Kohler residential standby fault codes — 10 codes (RDC2/DC2 controller)
• Briggs & Stratton Home Generator System blink codes — 8 codes (FC_1–FC_8 LED)

Why the same code doesn't mean the same thing twice

Unlike a furnace's simple blink count, generator manufacturers don't share one diagnostic format. Generac's Evolution and Nexus controllers show a 4-digit numeric code (or a plain warning like "Low Battery") right on the panel display. Kohler's RDC2 and DC2 controllers show the fault as plain text — "Over Crank," "Voltage High" — instead of a number. Briggs & Stratton's Home Generator System has no display at all; it reports faults as 1 to 8 blinks of a single LED, decoded as FC_1 through FC_8. If you're staring at a blinking light with no digits or text next to it, you're almost certainly looking at a Briggs & Stratton unit, and the blink count is the whole code.

What generator repairs typically cost

Broad U.S. ranges from contractor-rate aggregators, not a manufacturer price list — always get a local written quote, since parts, labor rates, and warranty coverage vary a lot by region and by dealer.

• Most standby generator repairs run roughly $150–$600 in parts and labor on top of a typical $75–$150 diagnostic/service-call fee, with the average whole-house repair bill landing near $270.
• Starting-battery replacement — the single most common standby-generator fix — runs about $200–$500 installed.
• A transfer switch replacement generally runs $200–$400 for the part plus a few hours of electrician labor.
• Control-board, alternator, or stator replacement is the most expensive common repair, typically $600–$1,200+ in parts and labor.
• Routine annual maintenance (oil, filters, spark plugs, battery test) typically costs $200–$600/year.

If your unit is still under manufacturer warranty, many of these repairs may be fully or partially covered — check warranty status before paying out of pocket. Sources: Angi, "Whole-House Generator Maintenance Cost," 2026; HomeGuide, "How Much Does a Generator Repair Cost," 2026.

See the full repair cost breakdown by job and by fault code for per-repair ranges across all three brands.