RPM Sensor Loss: No Valid Engine Speed Signal (Generac 1500-1522 Family)
The GENERAC-1518 (Generac Evolution) diesel fault code means: RPM Sensor Loss: No Valid Engine Speed Signal (Generac 1500-1522 Family). This is a serious severity code.
- Keep running?
- No — shut it down
- DIY difficulty
- easy
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What Are the Symptoms of GENERAC-1518?
- The generator fails to start, or shuts down unexpectedly while running, with a red light
- Mobile Link: "The generator has experienced a no crank RPM Sensor alarm. Please contact a dealer."
What Causes GENERAC-1518? (Most Likely First)
- Weak or bad battery Likely
- Fuel system problem Possible
- Overload or a sudden change in load Possible
- Missed routine maintenance Possible
Can I Keep Running It with GENERAC-1518?
No — shut it down. GENERAC-1518 is rated serious severity. Continuing to run the unit in this state risks further damage — get it looked at before putting it back in service.
Frequently Asked Questions
What does Generac code 1518 mean?
RPM sensor loss: the controller did not see a valid engine speed signal at startup, or lost it while running. Generac says owner troubleshooting is the same for every code in the range. Generac groups 1500-1522 under one alarm and does not publish a separate meaning for 1518.
Is it always the sensor?
No. Generac lists a weak battery, fuel problems, overload or a sudden load change, and missed maintenance as potential causes.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose GENERAC-1518?
Note when it happened: Generac troubleshoots a failure to start differently from a shutdown while running.
If it happened when starting, check the battery, battery terminals and cables. Generac notes home standby batteries last 3-5 years on average.
Clear the alarm and restart: on Evolution controllers press OFF, ENTER twice, then AUTO; on Power Zone 200 controllers hold OFF for 3 seconds. Never start the generator while it is under load.
If the code comes back after clearing it, Generac recommends a Generac Independent Authorized Service Dealer (IASD).
Sources 2
This page is built from documented references. Verify against your own service info before repair work.
- Generac Help Center, RPM Sensor Loss (1500-1522): RPM Sense Loss, error codes 1500-1522, red LED: "The controller does not detect a valid RPM signal during startup or has lost a valid RPM signal while running." "Potential Causes: Weak or bad battery, fuel system, overload condition, sudden load change, or lack of routine maintenance." "End-user troubleshooting remains the same regardless of the error code."
- Generac Help Center, "Where can I find a list of error codes for my generator" (the family table; an article for a base code "generally applies to all variants of that code").
Which Vehicles Commonly Get GENERAC-1518?
- Generac air-cooled home standby generators (Guardian and Next Generation series)
- Evolution controllers show the code on the display; Power Zone 200 controllers show it in Mobile Link
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