Generac Error Code 1505

What the code means, and the overcrank mix-up

Plenty of people call 1505 an overcrank code. Generac's own code list puts Overcrank at 1100 to 1101 and files 1505 under RPM Sense Loss, the 1500 to 1521 range. The difference matters when you talk to a dealer, so read them the exact number on the screen.

In practice the two alarms overlap. Overcrank means the unit turns over but won't start, and on Generac's support page the engine tries to crank 5 times before that alarm sets. RPM Sense Loss means the controller didn't see the engine come up to speed. Both send you to the same places: fuel, battery, air filter.

The 2012 air-cooled owner's manual describes the alarm as no valid RPM signal within 3 seconds of cranking.

Common causes

Generac lists a weak or bad battery, the fuel system, an overload, a sudden load change and missed maintenance. For a crank-but-no-start, the manual's troubleshooting table adds low fuel pressure or no fuel, fouled spark plugs, valve lash out of adjustment and a sticking choke.

Watch the propane gauge in a long outage. Generac says fuel pressure may be affected once an LP tank drops below about 30%, and its overcrank article says propane installs need at least a 250-gallon tank.

What you can safely check

1. Fuel valve. Make sure the shutoff on the gas line to the generator is open.
2. Fuel supply. On natural gas, check that your stove or furnace still lights and look for outage alerts from the gas company. On propane, read the tank gauge.
3. Fuel setting. Generac says the controller's fuel setting, and on some models the fuel jet, must match your fuel type.
4. Battery. Have it load tested; Generac puts typical life at 3 to 5 years. Check the terminals for corrosion and looseness.
5. Air and clearance. Look for a blocked or iced-up air filter, and keep a clear 3-foot area around the unit free of snow, leaves and brush.
6. Restart once. Clear the alarm, disconnect the house load, and start it with the MANUAL button. Never start it under load.

When to call a dealer

Fuel pressure, spark plugs and valve lash are dealer work. The manual gives fuel pressure specs of 10 to 12 inches of water column on LP and 5 to 7 on natural gas, and checking them takes a gauge and the model's service data. Call a Generac authorized service dealer if 1505 returns after your checks, if the unit won't start in AUTO during an outage, or if the code shows up during exercise. Leave the code on the display for the tech.