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Home / Generac / 1501

Evolution 1.0 / 2.0

1501

RPM sensor loss, twin cylinder running

Engine · Alarm

Alarm 1501 is RPM sensor loss on a twin-cylinder set that was already running. The table's causes are an air pocket in the fuel line, dirty fuel, or a missing ignition pulse from loss of one of the primary coils. The manual also describes a running RPM-signal loss of about one second, after which the controller shuts down, waits, and may try one re-crank before latching out.

Seen on: Air-cooled home standby generators with an Evolution 1.0 or 2.0 controller.

Likely causes

  • Fuel interruption, including an air pocket or dirty fuel, stalling a running engine.
  • Loss of an ignition pulse from a primary coil.
  • An overload that stalls the engine fast enough to drop the RPM signal.

Checks an owner can do

  1. Confirm the fuel supply is on and, on LP, that the tank is not empty.
  2. Note whether a large load started just as it died.
  3. Do not crank it repeatedly.

When to call a pro

Ignition coils and a stalled-engine diagnosis are technician tests. The manual treats a lost RPM signal as a latch-out, not a fuse to swap.

Source

Generac Diagnostic Repair Manual 10000041488 (Evolution 1.0/2.0 air-cooled). E-code rows below match that manual's alarm table as published by Home Generators for Sale and the manual text extracted from document 10000041488.

Wording follows that document. Firmware can change a threshold. If this page and the manual shipped with your unit disagree, follow the manual.

What fixed mine

No approved reports for this code yet. Send one. It stays in the review queue until it is approved.

Related Generac codes

https://generatorcodes.com/brand/generac/1501