Magnetic pickup sensor
Part: Generac 0G5885
Match before replacing for RPM sensor fault 1100 or RPM sense loss 1900 after checking sensor gap, resistance, and wiring.
$35
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Generac Generator Fault Codes
Generac residential and commercial standby generators (Guardian, CorePower, EcoGen, and Protector series) report faults via the Evolution or Nexus controller display. If the unit shows a code or blinking light and will not run, start with the controller fault history and the checks below.
Need a brand-neutral lookup first? Start with the generator fault-code hub to compare Generac, Kohler, Cummins Onan, Honda, Champion, Westinghouse, Briggs, and DuroMax fault patterns.
Two of the most common starting and shutdown faults are 1900 (RPM sense loss) and 1200 (overcrank). Start with those if the controller history does not show a clearer code. In many field checks, the fix is simpler than the code makes it sound: verify battery voltage, fuel supply, mag-pickup gap, and obvious wiring damage before ordering parts.
Generac Evolution Controller Error Codes
| Error Code | Fault Description | Common Cause | Action |
|---|---|---|---|
| 1100 | RPM sensor fault | Failed magnetic pickup or wiring | Check sensor gap (0.040”–0.060”), test resistance (200–600 ohms) |
| 1200 | Overcrank | Engine failed to start | Check fuel supply, spark, battery voltage |
| 1300 | Low oil pressure | Oil pressure below threshold | Check oil level, pressure switch, wiring |
| 1500 | Overspeed | Engine RPM exceeds 3750 | Test stepper motor, actuator linkage, governor springs |
| 1600 | Underspeed | Engine RPM below 2700 | Check load, fuel supply, stepper motor operation |
| 1700 | Field boost fail | Voltage regulator cannot excite field | Test DPE breaker, rotor resistance, regulator output |
| 1800 | High temperature | Engine coolant temp > 230°F | Check coolant level, radiator, fan operation |
| 1900 | RPM sense loss | Controller lost speed signal during run | Inspect mag pickup, wiring harness, controller |
| 2000 | Low battery | Battery voltage below 11.5V | Charge or replace battery, check charger output |
| 2100 | Overspeed shutdown | RPM exceeded safe max | Test stepper motor, check governor springs |
| 2200 | Underspeed shutdown | RPM dropped below minimum | Check fuel pressure, load capacity, air filter |
| 2300 | Voltage regulator failure | AVR output out of range | Test AVR, check rotor and stator windings |
| 2400 | Generator overvoltage | Output voltage too high | Test AVR adjustment, capacitor, regulator |
| 2700 | Main line contactor fail | Transfer switch fault | Test contactor coil, check control wiring |
| 2800 | Utility loss sense fail | Controller lost utility input | Check utility voltage, T1 fuse, wiring |
| 2900 | Exercise timer error | Internal clock fault | Reset controller, check battery backup |
| 3100 | Camshaft position sensor | No signal from cam sensor | Test sensor resistance, wiring, magnet alignment |
| 3200 | Throttle actuator failure | Stepper motor not responding | Test stepper motor windings (50–100 ohms), linkage binding |
| 3600 | Magneto ignition fault | No spark output | Check ignition module, kill wire short, spark plug gap |
| 4100 | Controller failure | Main board fault | Cycle controller power, replace control board if persists |
| 5400 | Fuel solenoid circuit fault | Solenoid open or short | Test solenoid resistance (20–40 ohms), check wiring |
| 5600 | Battery charger fault | Charger not outputting | Test charger output voltage (13.2–13.8V), check AC input |
Generac LED Flash Codes (Pre-Evolution Models)
Older Generac generators (pre-2005) with Nexus or earlier controllers use a single status LED to communicate faults by flash pattern. Many units remain in service after 20 years, but they offer less diagnostic detail than Evolution controllers.
| Flashes | Fault |
|---|---|
| 1 flash | Low oil pressure |
| 2 flashes | High temperature |
| 3 flashes | Overspeed |
| 4 flashes | Underspeed |
| 5 flashes | Overcrank |
| 6 flashes | RPM sensor loss |
| 7 flashes | Voltage regulator fault |
| 8 flashes | Battery voltage low |
Most Common Generac Faults
Error 1900 - RPM Sense Loss
Error 1900 is a common Generac standby-generator shutdown. The Evolution controller expects a valid RPM signal from the magnetic pickup sensor near the flywheel. When that signal drops out, the controller shuts down immediately.
The gap can drift after years of exercise cycles and thermal movement. Start with a simple gap check before replacing the sensor. A business card is about 0.020 inches thick; two cards stacked gives you about 0.040 inches before backing the sensor off. That check can resolve a 1900 code without touching a multimeter.
If the gap is right, test the pickup resistance (200-600 ohms). An open reading points to a failed sensor. Generac part 0G5885 is the replacement on many units, but match it to the exact model before ordering.
Error 1200 - Overcrank
The engine cranked its programmed three 15-second attempts but never fired. This is a catch-all that covers fuel, spark, battery, and mechanical problems. Start with battery voltage under crank and the fuel supply valve before replacing ignition or fuel-system parts.
Check the battery early because it is fast to verify. At rest it might read 12.5V, but under the starter load it drops. If it falls below 10V during crank, the controller may not get clean power and may never detect run. Also confirm the gas valve is open, especially after landscaping, fuel-line work, or maintenance.
Error 1300 - Low Oil Pressure
The oil pressure switch state varies by controller family, but the fault means the controller is not seeing the expected oil-pressure signal. Start with oil level, oil condition, the switch connector, and harness rub points near the cooling fan shroud. If the OEM procedure calls for a circuit test, lock out the generator and automatic transfer switch first, then verify switch continuity or oil pressure with the specified test method. Do not bypass the switch to run the engine as a shortcut.
Error 1500/2100 - Overspeed
The engine exceeded 3750 RPM on a 3600 RPM unit. Common checks include the stepper motor linkage, throttle plate movement, corrosion or debris at the pivot, and the demand-regulator diaphragm on gas-fueled units. With the generator locked out and safe to service, disconnect the stepper linkage from the throttle plate and move the plate by hand. If it binds, clean the pivot with carburetor cleaner. If it moves freely, test whether the stepper motor responds to controller commands.
Error 1700 - Field Boost Fail
The DPE circuit breaker on the control panel provides temporary battery voltage to excite the rotor field on startup. Reset the DPE breaker first. If it trips again immediately, check for a short in the brush holder or rotor winding. Test rotor resistance (18-35 ohms on many models). An open reading means the rotor may be burned open and needs a Generac dealer or generator repair shop.
Parts That May Need Replacement
| Part | Approx Cost | Typical Brands |
|---|---|---|
| Magnetic pickup sensor | $25–$45 | Generac 0G5885, 0J8499 |
| Stepper motor actuator | $60–$120 | Generac 0E6728, 0G5689 |
| Oil pressure switch | $15–$30 | Generac 0D4567, 0G0086 |
| AVR (voltage regulator) | $80–$200 | Generac 0F6004, 0G3947 |
| Battery charger board | $50–$90 | Generac 0E7346, 0G1811 |
| DPE circuit breaker (5A) | $10–$20 | Generac 0D4435 |
| Control board (Evolution) | $200–$500 | Generac 0G1440, 0H2226 |
| Fuel solenoid | $40–$80 | Generac 0G7711, 0E5951 |
Technician Tips
Generac generator fault codes appear as flashing LED patterns on older controllers. The red LED indicates a fault condition; green means normal operation. For low-oil-pressure faults, check oil level first, then the oil pressure switch. Generac generators have a built-in exercise cycle, and a failed exercise test can log a fault without an obvious warning light. Check the controller fault history for these events.
Maintenance: Generac recommends oil changes every 100 hours of operation or annually. Skipping oil changes accelerates wear, sludge buildup, and low-oil shutdowns, so log each service interval and verify the controller maintenance timer after service.
Need Replacement Parts?
Before ordering, match the generator part to the model number, controller generation, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
Automatic Transfer Switch Faults
If the generator runs but does not transfer power, inspect the ATS before condemning the generator. Utility sensing, transfer relays, and ATS control boards can all create the symptom: generator runs, house still dark.
When to Call a Pro
Generators involve 240V AC output and hazardous automatic starting. If you pull the brush holder and the slip rings are deeply grooved, or if the rotor resistance reads OL (open circuit), those are jobs for a Generac dealer with a rewind shop. The error code database is for diagnostic speed, not a substitute for proper safety gear on high-voltage systems.