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Home / Generac / 1505

Evolution 1.0 / 2.0

1505

RPM sensor loss, twin cylinder cranking

Engine · Alarm

Alarm 1505 is RPM sensor loss on a twin-cylinder set during cranking. The table points to a starter-motor problem or a missing ignition pulse from loss of one of the primary coils. The manual says that if a valid RPM signal is not seen within about three seconds of cranking, the controller shuts down and latches on RPM sensor loss.

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

Likely causes

  • Starter or crank circuit not turning the engine, so no RPM signal is produced.
  • Missing ignition pulse to the controller.

Checks an owner can do

  1. Confirm the battery cables are tight and the battery is not obviously dead. A weak battery can look like a sensor fault because the engine never turns fast enough.
  2. Stop after the lockout. Do not jump the starter.

When to call a pro

The manual notes that a common cause of RPM sensor loss is that the engine is not actually cranking. Starter and ignition-coil tests belong to a technician.

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/1505