Generac no rpm sense alarm - Generac Guardian 200 Amp Transfer Switch with Service Disconnect NEMA 3R

Contact them direct. This is an undocumented error. The obvious thing to do would be to reduce the engine speed?

https://www.generac.com/service-support/faqs/home-backup-error-codes/rpm-sense-loss-code-1501-1505-1511-1515

https://www.pramac.com/learningcenter

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If you have a Generac Generator which fails to start during a power outage and gives an Error Code 1518 - RPM Sense Loss you can try and manually get the generator restarted very simply. ... The generator should wait 5 seconds and then try and auto-start up to 3 times.
https://www.justanswer.com/small-engine/bwmwi-working-generator-generac-protector-qs-38kw.html

RPM Sensor Loss 1501
ALARM
This RPM alarm is set when a 2 cylinder unit was already running and stalled or lost the RPM signal from the ignition coils. Possible causes could be a fuel issue, the LP tank is empty, 1 or both ignition coils are damaged, or the unit was overloaded quick enough that the engine stalled and set the alarm.

Possibly a fuel flow issue.

Try running without load for awhile, if it faults with no load then either an ignition module or control board or fuel. If it only faults with significant load, then more likely a fuel flow or engine is stalling from sudden increase in load.

RPM Sense loss means that the generator controller hasn't received a valid signal from the ignition coils for 3 seconds of attempting to start. Probably a dead or low battery or bad ignition coil. Replace the battery and try again. Call dealer if problem persist.

please send me more info about this generator I need a model number is this a natural gas or propane I have a neighbor that just had one installed I might be able to get some info from him to help you

When you get the under speed alarm is the generator under load? Try manually starting the generator with no load and let it run for a while, if no alarm, then put it under your home load and measure current draw (maybe have an electrician check it) if the amp draw and in rush caused by compressors, pumps motors etc are within the generator rating, check your fuel pressure, on average 8-11 WC Nat gas. Pressure may test well under no load but drop starving the engine of fuel unde rload. Underspeed is just that engine cannot make RPM/Frequency

I would check the governor and the speed control - something is limiting the RPM when it should be at the factory setting. Could also be a restriction in the air filter.

I am sorry but you have selected the wrong product category. Please re-post in correct category. Thanks

I have the 18KW model and was told that most alarms relate to a low battery. Make sure the battery charger in the Transfer Switch is properly feeding the battery or hook up a mobil battery charger to the battery and see if the alarm goes away. Good Luck.

Sounds like Generator mode switch should be "ON".