Eaton UPS Alarm & Fault Codes: Complete Troubleshooting Guide

1. Identify your Eaton UPS model

Eaton’s UPS line covers everything from 650 VA desktop units to 2,000+ kVA hyperscale data center systems, and the alarm code conventions differ by family. Before looking up any code, identify which family your unit belongs to. The model number is printed on a label on the back or front of the unit, and on all modern models it is also shown on the LCD display in the System Information screen.

2. Beep pattern decoder (master table)

Before looking up any code, note the beep pattern. Eaton uses a consistent audio convention across almost all its UPS families, which means the beep alone narrows down the root cause significantly.

3. A-code alarm reference (A007–AC20)

A-codes are Eaton’s alarm codes — “minor” problems that reduce performance or prevent certain functions but do not immediately shut down the UPS. They should always be investigated, since many alarms precede a full fault condition if ignored. This table consolidates A-codes from the 9E, 93PM, 93PS, and related families.

4. F-code fault reference (F002–F811)

F-codes are Eaton’s fault codes — serious failures that typically power off the inverter and transfer the critical load to the bypass line. When an F-code appears, the UPS is no longer providing full protection, and continued operation risks load drop on the next power event.

5. 5P / 5PX / 5S / 9SX / 9PX small UPS codes

Eaton’s small single-phase UPS line uses simpler indicators than the three-phase units. Most faults trace back to four common causes: battery end-of-life, site wiring, overload, or ambient conditions.

6. 9130 / 9155 troubleshooting

The Eaton 9130 (0.7–6 kVA) is one of the most widely deployed mid-range UPS in Canadian IT and healthcare facilities — and also one of the most common sources of service calls, because the platform is retired and many units are now past their 3–5 year battery life. The 9155 (3–18 kVA) is similarly positioned — retired but still running in thousands of racks.

Both 9130 and 9155 are end-of-service-life from Eaton directly, meaning official parts and firmware updates are no longer guaranteed. However, they are still fully serviceable by independent specialists who maintain a parts inventory — a properly maintained 9130 or 9155 can easily run another 5–10 years in a clean environment. A professional service assessment is the right starting point before deciding repair vs. replace.

7. 9355 / 9390 / 93PM / 93PS enterprise codes

Eaton’s enterprise three-phase line is where most Canadian data center and hospital UPS service work happens. These units use the full A-code and F-code alarm system covered in sections 3 and 4, plus additional text messages on the LCD touchscreen. The touchscreen typically shows an active alarm list and a historical event log (often 500+ entries).

Key differences between the platforms:

• 9355 — older platform (now being superseded by 93PM G2); uses the standard A/F code set plus capacitor bank alarms (F300–F305).
• 9390 — retired, still running in many Canadian government buildings; parts availability varies.
• 93PM / 93PM G2 — flagship current-generation 30–400 kW; uses A/F codes plus PredictPulse remote monitoring alerts.
• 93PS — 91PS / 93PS single-phase input variant; same alarm conventions as 93PM.

For any alarm on these platforms, always export the event log before resetting anything. The event log frequently shows a cascade of precursor alarms before the active fault — information that disappears once you clear the alarm. For 93PM, PredictPulse (Eaton’s remote monitoring service) also captures this data in the cloud if subscribed.

8. 9395 / Power Xpert large-capacity alarms

The 9395 family (including 9395P, 9395XC, and legacy Power Xpert 9395) handles 200–2,250 kW installations — typically large data centers, hyperscale facilities, and the largest Canadian hospitals. The 9395 uses a touchscreen interface with four alarm severity categories (similar in concept to APC’s Galaxy VS):

The 9395 series is almost always deployed with PredictPulse remote monitoring. If you are seeing fault conditions on a 9395 without a monitoring subscription, adding remote monitoring is one of the highest-ROI operational investments available — serious faults typically give 24–72 hours of warning via precursor alarms if someone is actually watching.

9. Legacy Powerware (9155, 9170+, 5115, 9315) codes

Eaton acquired Powerware in 2004, and many Canadian government, university, and industrial sites still run Powerware-branded UPS from that era. These units are end-of-service-life, but a large installed base still generates service demand — particularly for battery replacement, capacitor refresh, and fan overhauls.

• Powerware 9315 (30–750 kVA) — heavy deployment in Canadian federal/provincial government and Crown corporations from the 1990s and 2000s. Many are now 20+ years old with capacitor failure risk.
• Powerware 9170+ (3–18 kVA) — retired. Uses the same A/F code conventions as later Eaton models.
• Powerware 9155 / 9125 / 9120 / 9130 — retired. Some use simpler alarm text rather than A-codes.
• Powerware 5115 / 5125 — smaller tower and rack units, long retired.
• Powerware FERRUPS (FE) — ferro-resonant design, scheduled EOSL 2027. Robust but aging — parts availability declining.

For any legacy Powerware unit showing a fault or alarm, the first conversation is usually service vs. replace. A proper assessment weighs remaining parts availability, battery string age, capacitor ESR, and total cost of ownership. Many Powerware units have another 5–10 years of life left with modest investment; others are at the end of the road. An independent Eaton and Powerware service assessment gives you the data to decide.

10. Battery alarms & battery mode notifications

Battery-related alarms are by far the most common reason an Eaton UPS starts alarming. The alarm hierarchy, in order of urgency:

Eaton batteries typically last 3–5 years in VRLA form, 8–10 years in Lithium. Battery life is cut in half for every 10°C above 25°C of ambient temperature, and high-cycling environments (frequent brownouts, generator tests) shorten life further. Proactive replacement before the alarm appears is standard practice — a degraded battery during an actual power event is functionally identical to having no UPS at all.

11. Overload alarms (A80E, A810)

Overload on an Eaton UPS means the connected load exceeds the unit’s rated continuous capacity. Two alarms cover this:

• A810 — load exceeded the user-defined warning threshold (typically set to 80% or 90%). This is a warning only; the UPS continues normal operation.
• A80E — load exceeds 105% of rated capacity. The UPS will typically alarm, then transfer to bypass or shut down if the overload persists.

Common sources of overload:

• Equipment added incrementally — a rack at 60% loading three years ago is now at 95% after server upgrades.
• Power supply failures in connected equipment drawing more current than rated.
• Inrush at startup — large blade servers or storage arrays can pull 2–3× steady-state load for a few seconds.
• Unauthorized loads — space heaters, kettles, or other high-draw equipment plugged into a UPS-protected outlet.

The first response is always to disconnect non-essential loads and see if the alarm clears. If it does, confirmed overload. If not, the UPS may have a sensor fault. Persistent overload on a business-critical UPS is a clear signal to review capacity planning and potentially upgrade.

12. Bypass mode indicators

When an Eaton UPS is in bypass mode, the critical load is running on raw utility power, bypassing the UPS inverter and batteries. The load is not protected from surges, sags, or outages.

Bypass is triggered for several reasons:

• Automatic bypass — internal fault forces the UPS to bypass to keep the load powered.
• Overload bypass — load exceeds inverter capacity; bypass is the only way to keep power flowing.
• Manual bypass (AC20) — technician has placed the unit in maintenance bypass intentionally.
• Energy Saver System (ESS) — a high-efficiency mode on 93PM-L and 9395 where the UPS runs in bypass with inverter on standby for faster efficiency. This is a design feature, not a fault.

A UPS in bypass should never be left unattended. It is either a signal that the UPS needs service, the load has grown beyond capacity, or a technician has active work in progress. For the 93PM and 9395 families, the event log shows exactly why bypass was entered — check the log before taking any action.

13. EPO activation (A806)

EPO — Emergency Power Off — is a hardwired safety system required by code in most Canadian data center and healthcare installations. Activating EPO immediately shuts down the UPS output and, on most models, also opens the battery breaker to fully de-energize the load. Once EPO is triggered, the UPS will not restart automatically — it must be manually reset.

Common triggers for A806:

• Intentional EPO activation — fire alarm, manual button, coordinated shutdown.
• Wiring fault on the EPO loop — a broken or high-resistance connection in the EPO monitoring circuit can trigger false EPO.
• Building alarm interface — on 93PM units with Building Alarm Monitoring connected to the fire panel, a fire alarm event can trigger EPO.

Before resetting A806, always confirm why it was triggered. If there is no evidence of a real emergency, investigate the EPO wiring loop for a fault before restoring the UPS to service. The EPO reset sequence varies by model — consult the unit’s installation manual or call a qualified technician.

14. Temperature & fan alarms

Eaton UPS have multiple thermal sensors — on the heatsinks (F004), inside the cabinet (ambient), on the battery, and on the transformer. Any one reaching the warning threshold triggers an alarm. Common root causes:

• Ambient too high — Eaton single-phase UPS rated for 0–40°C, three-phase for 0–40°C as well, but battery life halves for every 10°C above 25°C.
• Blocked airflow — A007 means a fan is blocked or failed. Check for debris in the intake, paper or cardboard against the rear exhaust, or HVAC supply-return problems.
• Failed fan — fans wear out. On enterprise units like 93PM, fans are a scheduled maintenance item (typically every 5–7 years).
• High load — running above 80% capacity generates substantially more heat.
• Dust accumulation — internal heat exchangers and filters clog, reducing cooling efficiency significantly.

Persistent temperature alarms are the fastest way to prematurely age capacitors, fans, and batteries — the entire UPS. Fixing them pays for itself in extended component life.

15. When to call a professional

We are professional UPS technicians, and we still recommend that facility staff handle certain checks themselves — verifying outlets, reseating battery connectors, clearing obvious ventilation blockages, disconnecting overload equipment, or noting which alarm code is active. These are low-risk actions that resolve many minor alarms without a service call.

However, the following conditions should always trigger a professional service call:

• Any F-code on any Eaton UPS — F-codes always indicate inverter or power-stage failure.
• Any fault on a 93PM, 93PS, 9355, 9390, or 9395 three-phase unit.
• A UPS stuck in bypass (AC20) that will not return to normal operation.
• Any A60D (battery disconnected) on a unit where batteries were not intentionally disconnected.
• Repeated A502 (charger voltage high) or A604 (battery voltage low) alarms.
• Any A806 (EPO active) where the EPO cause is unknown.
• Repeated temperature alarms (A007, F004).
• Any battery-related fault in a mission-critical environment (data centers, hospitals, telecom, government).
• Any Eaton UPS that has dropped its load during a power event.
• Any legacy Powerware unit (9315, 9390, 9170+) showing any alarm — parts availability may affect the repair plan.

The common thread: any fault involving internal electronics, three-phase equipment, battery strings over 100 VDC, or compliance-sensitive environments needs a technician with Eaton-specific test equipment, parts inventory, and proper training in coordinated shutdown procedures. Attempting internal diagnosis without that training can damage the UPS, damage connected equipment, and create serious electrical hazards.

Related resources

• Eaton & Powerware UPS Maintenance Canada — service plans, spare parts, and support
• UPS Battery Replacement & Repair Service Canada
• APC UPS Fault Codes & Beeping: Complete Troubleshooting Guide
• UPS Service for Data Centers
• UPS Service for Hospitals & Healthcare