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ErrBase

Generac Generator Code 1100: RPM Sense Loss

Quick Answer

Generac 1100 RPM sense loss means the controller stopped receiving the engine speed signal from the magnetic pickup sensor on the flywheel. Generac uses a Hall Effect magnetic sensor positioned near the flywheel ring gear teeth. As the flywheel spins, the teeth pass the sensor generating a pulse signal.

Generac 1100 RPM sense loss means the controller stopped receiving the engine speed signal from the magnetic pickup sensor on the flywheel. Generac uses a Hall Effect magnetic sensor positioned near the flywheel ring gear teeth. As the flywheel spins, the teeth pass the sensor generating a pulse signal. The most common cause is debris accumulation between the sensor and flywheel from engine vibration shaking loose rust, dirt, and metal particles. The sensor has a specific air gap (typically 0.030-0.040 inches) from the flywheel teeth - if debris fills this gap or the sensor shifts, the signal is lost. Clean the sensor face and verify the air gap first. The second most common cause is a corroded or loose wiring connector at the sensor.

GeneracGeneratorSeverity: highDifficulty: intermediate85% DIY Success
Time to Fix
30–90 min
Difficulty
intermediate
Parts Cost
$5 – $60
Tools Needed
Multimeter (resistance mode), Socket wrench set

What Does the 1100 Code Mean?

1100 means the engine speed sensor lost its signal. Clean the magnetic pickup sensor face and verify the air gap to the flywheel teeth (0.030-0.040 inches).

Most Likely Causes

Based on aggregated repair data, here is the probability breakdown for this error code:

Debris between sensor and flywheel teeth40%
Sensor air gap too wide from vibration24%
Sensor connector corroded14%
Wiring harness chafed or damaged12%
Magnetic pickup sensor failed10%

Symptoms You May Notice

  • 1100 alarm on controller
  • Engine was running then shut down
  • Engine speed may have fluctuated before shutdown
  • Generator lost power during operation
  • May coincide with other speed-related codes

Can you reset a Generac generator to clear the 1100 code?

Press ALARM RESET on the controller. Switch to AUTO mode. Test with MANUAL RUN to verify the fix. If 1100 appeared during an outage, the generator will auto-start on the next outage after reset.

Tools Required for Diagnosis

Multimeter (resistance mode)Socket wrench setFeeler gaugeContact cleaner sprayRag

Diagnostic Checklist

Follow these steps in order. We start with the easiest external fixes before opening up the machine.

1

Turn the controller to OFF

Turn the controller to OFF. Locate the RPM sensor (magnetic pickup) on the engine flywheel housing. It is a cylindrical sensor with a single connector, positioned near the flywheel teeth. Disconnect the connector and inspect for corrosion.

2

Remove the sensor (usually one bolt)

3

Measure the sensor resistance with a multimeter across the two

4

Reinstall the sensor with the correct air gap

Replacement Parts

If your diagnostic testing proves the component has failed, you will need a replacement. We recommend OEM parts over aftermarket for water-handling components.

Part Name
Generac RPM Magnetic Pickup Sensor0G5445 · $30–$60
Feeler gauge setN/A · $5–$10
Dielectric greaseN/A · $5–$8

Repair vs. Replace Calculator

Appliance Age (Years)7 Yrs
Labor Approach
Our Verdict
REPAIR
Estimated Cost: $33 (Parts) vs $9000 (New Machine)

Frequently Asked Questions

Can 1100 cause engine damage?
No. The controller shuts down the engine immediately when RPM sense is lost, preventing damage. The shutdown happens within seconds. However, you lose backup power until the alarm is cleared and the sensor issue is fixed.
My Generac shows 1100 only during exercise. Why not during outages?
The weekly exercise runs at a lower load than an actual outage. The vibration pattern at no-load can be different enough to shake the sensor or disturb debris. Check the sensor air gap and cleanliness.
How often should the RPM sensor be checked?
It is not in the standard annual service checklist, but cleaning the sensor face and checking the air gap during the annual oil change adds only 5 minutes and prevents the most common cause of 1100.

Related Generac Generator Error Codes

Code: HUBGenerac Generator Error Codes: Complete ReferenceCode: 2800Generac 2800: OvercrankCode: 1902Generac 1902: Governor Fault

Models Known to Experience 1100 Errors

This repair applies to most Generac generators with this error code. Common model numbers include:

Guardian 22kW 7043, Guardian 24kW 7210, Guardian 16kW 7035, EcoGen 15kW, Protector 20kW

Last verified for technical accuracy on March 15, 2026