1500 Serious Moderate DIY

Generac Generator 1500 — Overcrank

Generac Generator · Error code 1500

What 1500 Means

The engine cranked for the maximum allowed time (typically 16 seconds total across 3 attempts) without starting. Controller locked out further start attempts to protect the starter.

Symptoms

  • Hear starter cranking on outage but engine never fires
  • 1500 alarm on display
  • Generator does not transfer load
  • Battery may be drained after the event

Common Causes

1
No fuel pressure

Closed shutoff valve, empty propane tank, or low natural gas inlet pressure (must be 5-7 in WC NG, 10-12 in WC LP).

2
Stale fuel (gasoline portables)

Carbureted units sitting >90 days varnish the carb jets.

3
Weak battery

Cranks but RPM too low to fire — common in cold weather with a 3+ year battery.

4
Failed fuel solenoid

Solenoid does not open when the controller commands a start.

5
Failed spark/ignition

Coil, plug, or magneto failure prevents ignition.

6
Choke or stepper motor failure

Stepper motor on the carb/throttle body stuck — engine cannot draw correct mixture.

How to Fix It

  1. Verify fuel: confirm propane tank is not empty and shutoff valves to the generator are OPEN.
  2. On LP: pour hot (not boiling) water down the side of the tank — if frosted, tank is too small or too cold to vaporize. Switch to natural gas tap or larger tank.
  3. Pull and inspect spark plugs — replace with NGK BPR5ES (or spec plug) if fouled, gap to 0.030".
  4. Check battery: load-tested, should hold 12.4V+ at rest. Replace if >3 years or fails load test.
  5. Crank in Manual and listen at the fuel solenoid — should click. If silent, check wiring/replace solenoid.
  6. Confirm NG/LP inlet pressure with a manometer at the regulator. Adjust or call gas company if low.
  7. Clear the alarm (Enter + Off then Auto) only after fuel/spark/battery confirmed.

Parts You May Need

If diagnosis points to a failed part, these are the common replacements. As an Amazon Associate we earn from qualifying purchases.

Common replacement Spark plug (most air-cooled Guardian) View on Amazon→ Common replacement Generator battery 26R View on Amazon→ Common replacement Fuel regulator View on Amazon→

More Generac Generator Codes

0000 0000 — No Active Alarm (Healthy) 1100 1100 — Low Oil Pressure Shutdown 1300 1300 — High Engine Temperature 1501 1501 — Underspeed 1505 1505 — Overcrank (Variant — Try Again) 1600 1600 — Overspeed

All Generac codes → All generator codes →

Verified against manufacturer documentation: generac.com

Always unplug an appliance before servicing it. This guide is for informational purposes and is not a substitute for a qualified technician.