2800
Auxiliary Shutdown
An emergency stop (E-stop) switch was activated or left in the OFF position.
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Generator troubleshooting
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Shutdown / Critical
Shutdown and urgent alarm articles
2800 / 2801
E-Stop / Auxiliary Shutdown
Emergency stop or front-panel AUX shutdown rocker was activated.
2400
Fuse Problem
A blown fuse detected on the control board. Identify the cause before replacing.
2800
Generac Error Code 2800
Auxiliary Shutdown — Error Code 2800 Error Code 2800 indicates an Auxiliary Shutdown — the generator's control board has detected an open emergency stop (E-stop) circuit and halted the unit to prevent unsafe operation. Despite the alarming alert, this is typically one of the most straightforward issues to resolve. E-stop switch left in OFF position after maintenance Accidental bump flipping a switch to OPEN Dirty, corroded, or damaged switch contacts Loose or broken wiring in the safety circuit
1400
High Coolant Temperature
Coolant exceeded 246°F. Check coolant level and radiator airflow.
3700 / 3701
High Coolant Temperature
Engine coolant too hot. Check coolant level, radiator, thermostat, and fan.
2725 / 2735
High Oil Temp / Low Oil Level
Oil temperature exceeded 320°F or oil level below minimum.
1400 / 1401
High Temperature
Engine has overheated. Check airflow clearances, oil level, and air filter.
LOCKEDROTOR
Kohler Locked Rotor Alarm
Locked Rotor — Shutdown Alarm The Locked Rotor alarm means the controller sent a start command but detected no engine rotation within the preset time window (typically 2–3 seconds). To protect the starter motor from damage, the controller halts all crank attempts and locks out the unit until the fault is cleared. Despite the alarming name, the engine itself is often not physically seized — the most common cause is a weak or dead battery or a failed speed sensor. Dead or weak 12V battery (most common — 90% of cases) Failed magnetic pickup / speed sensor (no rotation signal) Faulty or stuck starter motor or solenoid Loose, corroded, or unseated wiring harness connectors Physically seized engine (debris, corrosion, extended storage) Worn or misaligned brushes / slip rings (generator end) Faulty controller / outdated controller firmware Faulty battery charger — not maintaining battery charge
LOCKEDROTOR
Kohler Locked Rotor Alarm
Locked Rotor — Shutdown Alarm The Locked Rotor alarm means the controller sent a start command but detected no engine rotation within the preset time window (typically 2–3 seconds). To protect the starter motor from damage, the controller halts all crank attempts and locks out the unit until the fault is cleared. Despite the alarming name, the engine itself is often not physically seized — the most common cause is a weak or dead battery or a failed speed sensor. Dead or weak 12V battery (most common — 90% of cases) Failed magnetic pickup / speed sensor (no rotation signal) Faulty or stuck starter motor or solenoid Loose, corroded, or unseated wiring harness connectors Physically seized engine (debris, corrosion, extended storage) Worn or misaligned brushes / slip rings (generator end) Faulty controller / outdated controller firmware Faulty battery charger — not maintaining battery charge
2720
Low Coolant Level
Coolant level sensor active for 5+ seconds. Check reservoir and inspect for leaks.
2720
Low Coolant Level
Coolant below the safe operating level. Liquid-cooled generators only.
2680 / 2681 / 2690
Low Fuel / Low Fuel Pressure
Fuel at 20% (warning), 10% (shutdown), or gas pressure below 5.2 in Hâ‚‚O.
1300 / 1301
Low Oil Pressure
Oil pressure below safe threshold. Check oil level immediately.
1300
Low Oil Pressure
Oil pressure dropped below the safe operating threshold. Check oil level and sensor.
1100
Overcrank
Engine failed to start after all programmed crank attempts.
1100 / 1101
Overcrank
Engine failed to start after multiple crank attempts. Usually fuel pressure, air in lines, or weak battery.
2100 / 2101 / 2111 / 2112
Overload
Output current exceeded rated capacity. Shed loads or check for short circuit.
2100 / 2102
Overload
Too many appliances running. Generator exceeded its rated capacity.
1200 / 1201
Overspeed
Engine speed exceeded the safe operating limit. Usually a governor failure or linkage issue.
1200 / 1205 / 1208
Overspeed
Engine exceeded 72 Hz (prolonged) or 75 Hz (instantaneous). Check governor wiring.
1800 / 1801
Overvoltage
Output voltage more than 10% above nominal. AVR or wiring fault.
1200 / 1205 / 1208
PZ410 1200 / 1205 / 1208 — Overspeed
1200 / 1205 / 1208 — Overspeed Engine RPM exceeded the safe operating limit. The PZ410 monitors three distinct Overspeed conditions, each with a different trigger: 1200 — Prolonged: over 72 Hz for 3 seconds. 1205 — Instantaneous: over 75 Hz for 1 second — the manual specifically notes 'Possible causes: broken stepper wire.' 1208 — DPE Measured: frequency more than 20% above target for 5 seconds. All three result in immediate shutdown to prevent mechanical damage. The most common cause on the PZ410/XG series is a governor or throttle body issue. Broken, loose, or disconnected throttle/governor stepper wire (code 1205)Governor motor failure or stuck throttle bodySudden large load shed causing RPM spikeIncorrect governor gain parameters (IASD adjustment required)Fuel pressure surge — propane regulator issueDPE (voltage regulator) sensing fault triggering false overspeed (1208)Firmware issue — update may be required
1300 / 1301
PZ410 1300 / 1301 — Low Oil Pressure
1300 / 1301 — Low Oil Pressure Oil pressure dropped below safe operating threshold. The PZ410 monitors two oil pressure conditions: 1300 (Shutdown Alarm) — the default extended alarm for low oil pressure while running. 1301 (Warning) — an early low oil pressure warning that allows continued operation but alerts the owner. The manual states for 1300: 'Occurred while running — Check the oil level.' For 1301: 'Check the oil level.' Do not ignore either — sustained low oil pressure causes catastrophic and irreversible engine damage. A faulty oil pressure sensor is also a common cause of false alarms on otherwise healthy engines. Low oil level — most common cause (oil burns off over time on liquid-cooled engines)Wrong oil viscosity for current operating temperatureDegraded oil that has lost viscosity — overdue oil changeFaulty or stuck oil pressure sensor (false alarm)Blocked oil filter or oil passageInternal oil leak — gasket or seal failureOil pump failure (rare)
1400
PZ410 1400 — High Coolant Temperature
1400 — High Coolant Temperature Coolant temperature exceeded 246°F — engine shut down to prevent damage. The PZ410 triggers alarm 1400 when coolant temperature exceeds 246°F (119°C) for 1 second. The manual description: 'Air Flow Impeded / Flow Issue — Check the inlet/outlet for debris. Coolant temp greater than 246°F (119°C) for 1 second. Check coolant sensor circuit for correct operation.' This is a liquid-cooled engine — the entire cooling system (coolant level, thermostat, water pump, radiator, and cooling fan) must function correctly. The PZ410 also monitors related warning codes: 1403 (High Coolant Temp Warning) and 1404 (Low Coolant Temp Warning) which fire before a full shutdown to give early notice. Low coolant level — insufficient coolant to absorb and transfer heatBlocked radiator fins (debris, insects, cottonwood, leaves)Failed thermostat stuck in closed positionFailed water pump or drive beltFailed cooling fan (electric or belt-driven)Generator overloaded in high ambient temperatureAir lock in the cooling systemFaulty coolant temperature sensor (false alarm)
1521 / 1522 / 1523 / 1524
PZ410 1521 / 1522 / 1523 / 1524 — RPM Sensor Loss
1521 / 1522 / 1523 / 1524 — RPM Sensor Loss Controller lost the engine speed sensing signal during cranking or operation. The PZ410 tracks four distinct RPM Sensor Loss conditions — more granular than the Evolution/Nexus controllers: 1521 — Missing tooth pulses while running (75 consecutive ms without signal). Possible causes: RPM sensor alignment, low battery. 1522 — After crank command, both RPM and DPE frequency read 0. Possible cause: failed motor. 1523 — After crank, flywheel teeth count AND DPE frequency both read 0. Possible cause: failed motor. 1524 — Flywheel RPM and DPE-derived RPM differ by 100+ RPM for 300ms, or both sensors invalid simultaneously. Each code points to a different location in the speed sensing system. Weak or dead battery — crank speed too slow to generate reliable MPU signal (1521)MPU sensor out of alignment or air gap too largeFailed MPU sensor — no signal outputBroken or loose wiring between MPU sensor and PZ410 (J2 throttle connector)Failed starter motor — engine not actually cranking (1522/1523)Damaged flywheel ring gear teethDPE wiring fault — loss of voltage regulator feedback signal (1524)
1800 / 1801
PZ410 1800 / 1801 — Overvoltage
1800 / 1801 — Overvoltage Generator output voltage exceeded safe operating limits. The PZ410 monitors two Overvoltage conditions: 1800 — Prolonged: output voltage more than 10% above nominal for 3 seconds. 1801 — Instantaneous: an instantaneous measurement 30% over nominal. Both trigger immediate shutdown to protect connected appliances and the generator's alternator. The PZ410's digital AVR (Automatic Voltage Regulator) continuously adjusts field current to maintain ±0.5% voltage regulation — overvoltage almost always indicates the AVR has lost control, which is typically an electrical fault rather than a mechanical one. AVR (Automatic Voltage Regulator) failure or loss of controlSudden large load shed causing voltage spikeFaulty AVR feedback wiring or DPE sensing circuit (J1 AVR connector)Incorrect AVR voltage setpoint parameterFailed excitation winding in the rotor (AVR cannot regulate properly)Short circuit in the voltage sensing circuitController firmware issue
1900 / 1901 / 1902 / 1906 / 1907
PZ410 1900 / 1901 / 1902 / 1906 / 1907 — Undervoltage
1900 / 1901 / 1902 / 1906 / 1907 — Undervoltage Generator output voltage dropped below safe operating threshold. The PZ410 has five Undervoltage conditions, each diagnosing a different location: 1900 — Prolonged: voltage below 80% of nominal for 10+ seconds. 1901 — Instantaneous: voltage below 15V for 2 seconds. 1902 — Both Zero Crosses Missing: 'Undervoltage due to faulty excitation winding, or zero cross circuit, or circuit in general. Both zero crosses missing for 1.5 seconds. Possible cause: loose wiring, field boost hardware failure.' 1906 — Single Zero Cross Missing: same causes as 1902 but only one of two zero cross signals missing. 1907 — Post-Loadshed Undervoltage: generator commanded back to full speed after loadshed but still undervoltage — indicates overload condition persists. Generator overloaded — exceeding rated kVA capacity (1900, 1907)Faulty or worn alternator brushes / slip rings — reduced excitation currentAVR failure — cannot maintain field excitationFaulty excitation winding in the rotorLoose or broken DPE wiring (J1 connector, pins 1 and 3) — codes 1902/1906Failed field boost hardware (1902/1906)Loose connections on output terminals or transfer switch
2100 / 2101 / 2111 / 2112
PZ410 2100 / 2101 / 2111 / 2112 — Overload
2100 / 2101 / 2111 / 2112 — Overload Generator output current exceeded rated capacity. The PZ410 monitors four Overload conditions using different detection methods: 2100 — CT-based overload: output current from CT sensors above threshold. 2101 — DPE/Field Current overload: field current above threshold. 2111 — Overcurrent/I²T: current exceeds 150% of rated, typically from a phase-to-phase or phase-to-neutral short. The controller runs a PID algorithm to prevent stalling. 2112 — I²T Based Detection: output current above rated limit accumulates to 300% within 11 seconds — sustained overload protection. Notably, the PZ410 has built-in overload control that eliminates the need for a circuit breaker on XG series generators. Too many appliances running simultaneously — load exceeds rated kWLarge motor startup surge (central A/C, well pump, electric motors)Short circuit in connected wiring or appliances (especially 2111/2112)Ground fault in connected wiringGenerator undersized for the critical load panelFaulty CT (current transformer) sensors — false overload reading
2680 / 2681 / 2690
PZ410 2680 / 2681 / 2690 — Low Fuel / Low Fuel Pressure
2680 / 2681 / 2690 — Low Fuel / Low Fuel Pressure Fuel level or fuel pressure is below operating requirements. The PZ410 monitors three fuel-related conditions: 2680 (Warning) — low fuel level switch active for 1 minute. The sensor triggers at 20% fuel remaining. Unit continues to run. 2681 (Shutdown Alarm) — fuel level below 10%. Unit shuts down. 2690 (Warning) — low fuel pressure: switch active when pressure falls below 5.2 in H₂O ±0.4 in (below 0.19 psi). Unit continues to run but pressure is dangerously low. These codes are especially critical in Florida where propane demand spikes during hurricane season. Propane tank running low — below 20% for 2680, below 10% for 2681Manual gas shutoff valve partially or fully closedLP regulator failure — not maintaining adequate pressureNatural gas supply pressure drop during peak demandFrozen propane regulator in cold weatherFuel sender/float failure — false low readingClogged fuel filter or fuel lines
2720
PZ410 2720 — Low Coolant Level
2720 — Low Coolant Level Coolant level sensor detected low coolant for more than 5 seconds. The PZ410 triggers alarm 2720 when the low coolant digital input is active for more than 5 seconds. This is specific to liquid-cooled XG series generators. Operating a liquid-cooled engine with insufficient coolant causes rapid overheating — head gasket failure, warped cylinder heads, or cracked engine block can occur within minutes. The 5-second confirmation window prevents false alarms from coolant sloshing during startup, but once the alarm fires it must be taken seriously. Coolant loss through a slow external leak (hose, radiator, water pump)Internal coolant leak (head gasket failure — coolant burns off or mixes with oil)Normal evaporation from the overflow reservoir over timeFaulty coolant level sensor — false alarmImproper coolant mixture (too dilute, freezes and cracks components)Radiator pressure cap failure allowing coolant to escape under pressure
2750 / 2751 / 2760
PZ410 2750 / 2751 / 2760 — Battery Warning / Very Low Battery / Battery Problem
2750 / 2751 / 2760 — Battery Warning / Very Low Battery / Battery Problem Battery voltage is critically low or the charging system has a problem. The PZ410 has three battery-related codes with different severity: 2750 (Warning) — battery voltage below 12.1V for 1 minute. Unit continues to run. 2751 (Shutdown Alarm) — battery voltage below 9.0V for 60 seconds. Unit shuts down and locks out. This is unique to the PZ410 — the Evolution/Nexus controllers do not have a Very Low Battery shutdown. 2760 (Warning) — battery voltage is above 16V OR charge current is above 600mA at the end of an 18-hour charge cycle — indicating the battery may have failed internally. Battery at end of service life — internal capacity loss (2750/2751)Battery charger circuit breaker tripped inside generator cabinetCharger not receiving 120V AC (GOT_T1 input disconnected) — raises separate 2780 faultBattery with internal short — drawing excess current (2760)Battery overcharge from external charger malfunction (2760)Corroded or loose battery terminals reducing charging efficiencyBattery older than 4–5 years losing capacity to hold charge
2770 / 2780
PZ410 2770 / 2780 — Charger Warning / Charger Missing AC
2770 / 2780 — Charger Warning / Charger Missing AC The battery charging system has a fault or is not receiving utility power. 2770 — Charger Warning: battery voltage is above 16.1V at any time (overcharge), OR battery voltage remains below 12.5V after completing the 26-hour charge cycle. This indicates either an overcharging condition or the battery has failed and cannot hold charge. 2780 — Charger Missing AC: the AC input to the internal battery charger is missing for more than 5 minutes during a charging attempt. The PZ410 detects this via the GOT_T1 digital input. Without AC input, the internal charger cannot function — the battery will slowly drain until a 2750 Low Battery or 2751 Very Low Battery shutdown occurs. 2770: Battery failing internally — cannot hold charge after full cycle2770: Battery overcharging from external charger malfunction2770: Charger fault at end of charge cycle — battery voltage still low2780: Utility AC power to the generator not present (power outage when generator is in standby)2780: Charger circuit breaker tripped inside generator cabinet2780: Loose or broken wiring on the J7 charger connector (HOT and Neutral AC input)2780: GFCI outlet tripped if generator power is connected through a GFCI circuit
SVC A / SVC B / Battery Maint
PZ410 SVC A / SVC B / Battery Maint — Service Schedule Due
SVC A / SVC B / Battery Maint — Service Schedule Due The PZ410 has reached a programmed maintenance interval. The PZ410 tracks maintenance intervals and displays reminders when service is due. These appear on the Alarm Screen with an M prefix (Maintenance reminder) rather than an A (Alarm) or W (Warning). The unit continues to operate normally. The PZ410 Maintenance Log (Info Screen → Maintenance Log) records all service events. Service reminders include Service Schedule A (annual/light service), Service Schedule B (comprehensive 2-year/200-hour service), and Battery Maintenance Due (battery inspection/replacement reminder). Ignoring these reminders leads to degraded performance and increased fault frequency. Generator has reached the annual or 200-hour service intervalBattery maintenance interval reached (typically every 2–3 years)Service was previously deferredController has been tracking hours and calendar time since last service reset
1501 / 1505
RPM Sense Loss
Controller cannot detect engine rotation. Weak battery, speed sensor, or ignition coil fault.
1521 / 1522 / 1523 / 1524
RPM Sensor Loss
Speed sensing signal lost during cranking or operation. Battery or MPU sensor.
1600 / 1603
Underspeed
Engine speed dropped below threshold. Likely overload or fuel delivery issue.
1600
Underspeed / Overloaded
RPM below 83.3% of target for 30 seconds. Overload or fuel issue.
1900 / 1901 / 1902 / 1906 / 1907
Undervoltage
Output voltage below 80% of nominal. Overload, AVR, brushes, or DPE wiring.
1900 / 1902
Undervoltage
Generator output voltage too low. Faulty AVR, overload, or worn brushes/slip rings.
Warning / Monitor
Monitor and maintenance articles
2750 / 2751 / 2760
Battery Warning / Very Low Battery
2751 is a SHUTDOWN alarm unique to PZ410 (battery below 9.0V). Act before it shuts down.
2770
Charger Warning
Built-in battery charger is failing or not receiving power. Battery will drain.
2770 / 2780
Charger Warning / Missing AC
Battery charger fault or no AC input. Battery will drain if unaddressed.
2750
Low Battery
Battery voltage below 12.1V for 60+ seconds. Act now before it causes a shutdown.
SVC A / SVC B
Service Schedule Due
Generator has reached a maintenance interval. Schedule service to maintain warranty.
SVC A / SVC B / Battery Maint
Service Schedule Due
PZ410 has reached a maintenance interval. Schedule service to maintain warranty.
Dealer / Service Required
Professional service required
Sensor Faults · ECU · Controller · Governor · Transfer Switch · Ignition Coils
IASD-Required Alarm Reference
Complete reference table of all PZ410 codes requiring Generac-authorized dealer service. Includes 40+ fault codes with descriptions and actions.
Article
PZ410 IASD-Required Alarms
