Do not get left in the dark!
Generac PZ410
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
Need a technician now? Skip the troubleshooting — open a service ticket and we'll handle it.
⚠ SAFETY FIRST: Always press OFF on the PZ410 before inspecting components — this prevents automatic starts. Disconnect battery (negative lead first) before touching wiring. This generator can auto-start.
Overview
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
Synced from the client troubleshooting workflow library. The frontend article uses the client layout source for this entry.
Generator overloaded — exceeding rated kVA capacity (1900, 1907)
Faulty or worn alternator brushes / slip rings — reduced excitation current
AVR failure — cannot maintain field excitation
Faulty excitation winding in the rotor
Loose or broken DPE wiring (J1 connector, pins 1 and 3) — codes 1902/1906
Failed field boost hardware (1902/1906)
Loose connections on output terminals or transfer switch
Step-by-step workflow
Navigate to PZ410 Power Screen Page 1 and check generator voltage on all phases. If voltage is low and generator is near rated capacity — overload is likely.
Codes 1902 and 1906 specifically point to the zero cross / DPE wiring. With generator OFF and battery disconnected, inspect the J1 AVR connector.
Worn brushes or dirty slip rings reduce the excitation current that the AVR uses to maintain output voltage.
After addressing the root cause, clear the alarm and watch voltage on Power Screen Page 1 during startup.
After reset
The code cleared and the unit returned to standby. Log the incident, confirm ready-to-run status, and monitor the next exercise cycle.
If the code returns immediately, stop resetting and move into service. The issue likely needs inspection of wiring, switches, or a controller-level component.
Prevention
Brushes wear gradually. Annual inspection prevents unexpected voltage failures.
PZ410 Power Screen Page 3 shows live generator kW — keep below 80% of rated output.
A&A Power Generators performs full voltage output and AVR testing at every service visit. +1-888-991-6933
Inspect J1 AVR connector and DPE wiring at every service — vibration loosens these critical connections.
Outdated firmware can affect AVR regulation thresholds. Update via Settings → Firmware Update.
Receive Undervoltage warnings immediately to protect sensitive appliances.
Let A&A Power Generators handle all preventative maintenance for your Generac XG/Protector generator.
Still need help?
If the issue persists after following the workflow, route the unit into ticket, appointment, or consultation support so the team can take over with the right service path.
