Where can I find the official Felicity Apollo-5KLP1G01-MX error code manual?

Each code on this page lists the official source manual filename and page number at the bottom. The manuals are published by Felicity on their website; we compile the codes here so you can search across all of them at once instead of opening each PDF.

Is the Apollo-5KLP1G01-MX the same as other Felicity models?

Some Felicity units share firmware across a family of variants — the same fault codes apply to multiple model numbers. Look at the "also covers" chips below the title to see which other model numbers this page applies to.

What's the most critical code on a Felicity Apollo-5KLP1G01-MX?

Critical-severity codes (red dot) are the ones that trip the unit offline immediately — typically short-circuit, IGBT, or BMS hardware failures. These are listed first when you filter by severity. Do not bypass them; they indicate a hardware or safety condition that requires service.

What does F01 mean on Apollo-5KLP1G01-MX?

PV input voltage exceeds the allowed maximum. Cause: PV voltage is too high. Fix: Reduce the number of PV modules in series.

What does F02 mean on Apollo-5KLP1G01-MX?

Over current detected at PV port. Cause: Over current happen at PV port. Fix: Restart the unit, if the error persists, contact the repair center.

What does F04 mean on Apollo-5KLP1G01-MX?

Short circuit happen at PV port. Cause: Short circuit happen at PV port. Fix: Check if wiring is connect well.

What does F06 mean on Apollo-5KLP1G01-MX?

PV current sensor failed. Cause: PV current sensor failed. Fix: Restart the unit, if the error persists, contact the repair center.

What does F07 mean on Apollo-5KLP1G01-MX?

Battery voltage exceeds the maximum allowed value. Cause: Battery voltage is too high. Fix: Check if spec and quantity of batteries are meet requirements.

What does F10 mean on Apollo-5KLP1G01-MX?

Abnormal LLC converter operation. Cause: Abnormal LLC. Fix: Restart the unit, if the error persists, contact the repair center.

What does F11 mean on Apollo-5KLP1G01-MX?

Over current detected at the Buckboost stage. Cause: Over current at Buckboost. Fix: Restart the unit, if the error persists, contact the repair center.

What does F14 mean on Apollo-5KLP1G01-MX?

BuckBoost converter is out of balance. Cause: BuckBoost is out of balance. Fix: Restart the unit, if the error persists, contact the repair center.

What does F15 mean on Apollo-5KLP1G01-MX?

Buckboost current sensor failed. Cause: Buckboost current sensor failed. Fix: Restart the unit, if the error persists, contact the repair center.

What does F16 mean on Apollo-5KLP1G01-MX?

Number 2 Buckboost current sensor failed. Cause: NO.2 Buckboost current sensor failed. Fix: Restart the unit, if the error persists, contact the repair center.

What does F17 mean on Apollo-5KLP1G01-MX?

Overload condition timed out. Cause: Overload time out. Fix: Reduce the connected load by switching off some equipment.

What does F19 mean on Apollo-5KLP1G01-MX?

Output short circuit detected. Cause: Output short circuited. Fix: Check if wiring is connected well and remove abnormal load.

What does F20 mean on Apollo-5KLP1G01-MX?

Input and output wiring reversed. Cause: Input output reverse. Fix: Confirm that the input and output wiring is correct.

What does F21 mean on Apollo-5KLP1G01-MX?

Output current sensor failed. Cause: Output current sensor failed. Fix: Output current sensor failed.

What does F22 mean on Apollo-5KLP1G01-MX?

Output voltage is too low. Cause: Output voltage is too low. Fix: Reduce the connected load.

What does F23 mean on Apollo-5KLP1G01-MX?

Output voltage is too high. Cause: Output voltage is too high. Fix: Restart the unit, if the error persists, contact the repair center.

What does F24 mean on Apollo-5KLP1G01-MX?

Over current or surge detected by software protection. Cause: Over current or surge detected by software. Fix: Restart the unit, if the error persists, contact the repair center.

What does F25 mean on Apollo-5KLP1G01-MX?

Hardware detected over current at inverter port. Cause: Hardware detect over current at inverter port. Fix: Restart the unit, if the error persists, contact the repair center.

What does F26 mean on Apollo-5KLP1G01-MX?

Invert soft start failed; internal components failed. Cause: Internal components failed. Fix: Restart the unit, if the error persists, contact the repair center.

What does F28 mean on Apollo-5KLP1G01-MX?

The DC component of the inverter current is abnormal. Cause: The DC component of the inverter current is abnormal. Fix: Restart the unit, if the error persists, contact the repair center.

What does F29 mean on Apollo-5KLP1G01-MX?

Inverter current sensor failed. Cause: Inverter current sensor failed. Fix: Restart the unit, if the error persists, contact the repair center.

What does F30 mean on Apollo-5KLP1G01-MX?

Bus voltage is too low. Cause: Bus voltage is too low. Fix: Restart the unit, if the error persists, contact the repair center.

What does F31 mean on Apollo-5KLP1G01-MX?

Bus voltage is too high; AC surge or internal components failed. Cause: AC Surge or internal components failed. Fix: Restart the unit, if the error persists, contact the repair center.

What does F33 mean on Apollo-5KLP1G01-MX?

Bus soft start failed; internal components failed. Cause: Internal components failed. Fix: Restart the unit, if the error persists, contact the repair center.

What does F34 mean on Apollo-5KLP1G01-MX?

Over temperature condition at the heat sink. Cause: Over temperature happen at heat sink. Fix: Check whether the ambient temperature is too high.

What does F35 mean on Apollo-5KLP1G01-MX?

Inner temperature exceeds the allowed limit. Cause: The inner temperature over. Fix: Check whether the ambient temperature is too high.

What does F38 mean on Apollo-5KLP1G01-MX?

Leakage current fault detected. Cause: Leakage current fault. Fix: Restart the unit, if the error persists, contact the repair center.

What does F39 mean on Apollo-5KLP1G01-MX?

Leakage current sensor failed. Cause: Leakage current sensor failed. Fix: Restart the unit, if the error persists, contact the repair center.

What does F42 mean on Apollo-5KLP1G01-MX?

Relay self-check failure. Cause: Relay check failure. Fix: Restart the unit, if the error persists, contact the repair center.

What does F43 mean on Apollo-5KLP1G01-MX?

Parallel CAN communication abnormality. Cause: Parallel CAN COMM abnormality. Fix: Test the parallel communication line, restart still have problems please contact the after-sales service.

What does F44 mean on Apollo-5KLP1G01-MX?

Loss of parallel hosts in parallel system. Cause: Loss of parallel hosts. Fix: Test the parallel communication line, restart still have problems please contact the after-sales service.

What does F45 mean on Apollo-5KLP1G01-MX?

Parallel synchronisation signal abnormal. Cause: Parallel Synchronisation Signal Abnormal. Fix: Test the parallel communication line, restart still have problems please contact the after-sales service.

What does F49 mean on Apollo-5KLP1G01-MX?

Parallel negative power protection triggered. Cause: Parallel negative power protection. Fix: Restart the unit, if the error persists, contact the repair center.

What does F50 mean on Apollo-5KLP1G01-MX?

EEPROM failure. Cause: EEPROM failure. Fix: Restart the unit, if the error persists, contact the repair center.

What does F51 mean on Apollo-5KLP1G01-MX?

DSP1 communication failure. Cause: DSP1 communication failure. Fix: Restart the unit, if the error persists, contact the repair center.

What does F52 mean on Apollo-5KLP1G01-MX?

DSP2 communication failure. Cause: DSP2 communication failure. Fix: Restart the unit, if the error persists, contact the repair center.

What does F54 mean on Apollo-5KLP1G01-MX?

Temperature sensor disconnected. Cause: Temperature sensor disconnected. Fix: Restart the unit, if the error persists, contact the repair center.

What does F87 mean on Apollo-5KLP1G01-MX?

Battery input circuit failure. Cause: Battery input circuit failure. Fix: Restart the unit, if the error persists, contact the repair center.

What does W09 mean on Apollo-5KLP1G01-MX?

Overload warning. Audible alarm: beep twice every second. Fix: Reduce the loads.

What does W25 mean on Apollo-5KLP1G01-MX?

Phase sequence error warning between input and output AC power lines. Fix: Check that the input and output power lines correspond.

Apollo-5KLP1G01-MX

Energy storage system49 codes

also coversApollo-5KLP1G01-M1Apollo-5KLP1G01-M2Apollo-4K6LP1G01-MXApollo-4K6LP1G01-M1Apollo-4K6LP1G01-M2

27 Critical 16 Fault 6 Warning

About the Felicity Apollo-5KLP1G01-MX

The Felicity Apollo-5KLP1G01-MX is a Energy storage system unit covered by a shared firmware family that includes 6 variants. The error codes listed below apply to every variant in this family — Apollo-5KLP1G01-MX, Apollo-5KLP1G01-M1, Apollo-5KLP1G01-M2, Apollo-4K6LP1G01-MX and 2 others. If your unit's exact model number isn't shown in the title but is listed in the "also covers" tags, this is the correct reference page.

How to use this page

Each row below shows an error code, its severity, and a brief description. Click any row to expand the full cause and the recommended fix. The severity dot tells you whether the unit will keep operating (warning), derate (fault), or trip offline (critical). For codes that require an authorized service partner, the recommended-fix block says so explicitly.

F01PV voltage is too high.Fault

Description

PV input voltage exceeds the allowed maximum.

Cause

PV voltage is too high.

Recommended fix

Reduce the number of PV modules in series.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 42

F02Over current happen at PV port.Fault

Description

Over current detected at PV port.

Cause

Over current happen at PV port.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 42

F04Short circuit happen at PV port.Critical

Description

Short circuit happen at PV port.

Cause

Short circuit happen at PV port.

Recommended fix

Check if wiring is connect well.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 42

F06PV current sensor failed.Critical

Description

PV current sensor failed.

Cause

PV current sensor failed.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 42

F07Battery voltage is too high.Fault

Description

Battery voltage exceeds the maximum allowed value.

Cause

Battery voltage is too high.

Recommended fix

Check if spec and quantity of batteries are meet requirements.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 42

F10Abnormal LLC.Critical

Description

Abnormal LLC converter operation.

Cause

Abnormal LLC.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 42

F11Over current happen at Buckboost.Critical

Description

Over current detected at the Buckboost stage.

Cause

Over current at Buckboost.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 42

F14BuckBoost is out of balance.Critical

Description

BuckBoost converter is out of balance.

Cause

BuckBoost is out of balance.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 43

F15Buckboost current sensor failed.Critical

Description

Buckboost current sensor failed.

Cause

Buckboost current sensor failed.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 43

F16NO.2 Buckboost current sensor failed.Critical

Description

Number 2 Buckboost current sensor failed.

Cause

NO.2 Buckboost current sensor failed.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 43

F17Overload time out.Fault

Description

Overload condition timed out.

Cause

Overload time out.

Recommended fix

Reduce the connected load by switching off some equipment.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 43

F19Output short circuited.Critical

Description

Output short circuit detected.

Cause

Output short circuited.

Recommended fix

Check if wiring is connected well and remove abnormal load.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 43

F20Input output reverse.Fault

Description

Input and output wiring reversed.

Cause

Input output reverse.

Recommended fix

Confirm that the input and output wiring is correct.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 43

F21OP current sensor failed.Critical

Description

Output current sensor failed.

Cause

Output current sensor failed.

Recommended fix

Output current sensor failed.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 43

F22Output voltage is too low.Fault

Description

Output voltage is too low.

Cause

Output voltage is too low.

Recommended fix

Reduce the connected load.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 43

F23Output voltage is too high.Critical

Description

Output voltage is too high.

Cause

Output voltage is too high.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 43

F24Over current or surge detected by Software.Critical

Description

Over current or surge detected by software protection.

Cause

Over current or surge detected by software.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 43

F25Hardware detect over current at inverter port.Critical

Description

Hardware detected over current at inverter port.

Cause

Hardware detect over current at inverter port.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 43

F26Invert soft start failed.Critical

Description

Invert soft start failed; internal components failed.

Cause

Internal components failed.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 43

F28The DC component of the inverter current is abnormal.Critical

Description

The DC component of the inverter current is abnormal.

Cause

The DC component of the inverter current is abnormal.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 43

F29Inverter current sensor failed.Critical

Description

Inverter current sensor failed.

Cause

Inverter current sensor failed.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 43

F30Bus voltage is too low.Critical

Description

Bus voltage is too low.

Cause

Bus voltage is too low.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 43

F31Bus voltage is too high.Critical

Description

Bus voltage is too high; AC surge or internal components failed.

Cause

AC Surge or internal components failed.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 43

F33Bus soft start failed.Critical

Description

Bus soft start failed; internal components failed.

Cause

Internal components failed.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 43

F34Over temperature happen at heat sink.Fault

Description

Over temperature condition at the heat sink.

Cause

Over temperature happen at heat sink.

Recommended fix

Check whether the ambient temperature is too high.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 43

F35The inner temperature over.Fault

Description

Inner temperature exceeds the allowed limit.

Cause

The inner temperature over.

Recommended fix

Check whether the ambient temperature is too high.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 43

F38Leakage current fault.Critical

Description

Leakage current fault detected.

Cause

Leakage current fault.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 43

F39Leakage current sensor failed.Critical

Description

Leakage current sensor failed.

Cause

Leakage current sensor failed.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 43

F40Isolation resistance to ground of the PV string is too low.Critical

Description

Isolation resistance to ground of the PV string is too low.

Cause

Isolation resistance to ground of the PV string is too low.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 44

F42Relay check failure.Critical

Description

Relay self-check failure.

Cause

Relay check failure.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 44

F43Parallel CAN COMM abnormality.Fault

Description

Parallel CAN communication abnormality.

Cause

Parallel CAN COMM abnormality.

Recommended fix

Test the parallel communication line, restart still have problems please contact the after-sales service.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 44

F44Loss of parallel hosts.Fault

Description

Loss of parallel hosts in parallel system.

Cause

Loss of parallel hosts.

Recommended fix

Test the parallel communication line, restart still have problems please contact the after-sales service.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 44

F45Parallel Synchronisation Signal Abnormal.Fault

Description

Parallel synchronisation signal abnormal.

Cause

Parallel Synchronisation Signal Abnormal.

Recommended fix

Test the parallel communication line, restart still have problems please contact the after-sales service.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 44

F46Inconsistency in parallel versions.Fault

Description

Inconsistency in firmware versions across paralleled inverters.

Cause

Inconsistency in parallel versions.

Recommended fix

1. Update all inverter firmware to the same version. 2. Check the version of each inverter via the LCD settings to ensure that the CPU versions are the same. if it is not the same, please contact after-sales personnel to update the firmware. 3. After updating, if the problem still exists, please contact after-sales.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 44

F47Inconsistent parallel settings.Fault

Description

Inconsistent parallel settings; single-phase parallel system and group three-phase system setup error.

Cause

Single-phase parallel system and group three-phase system setup error.

Recommended fix

Single-phase parallel system and group three-phase system setup error.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 44

F48Failure of the parallel system as a whole.Fault

Description

Failure of the parallel system as a whole; specific faults in other machines in the parallel system.

Cause

Specific faults in other machines in the parallel system.

Recommended fix

Specific faults in other machines in the parallel system.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 44

F49Parallel negative power protection.Fault

Description

Parallel negative power protection triggered.

Cause

Parallel negative power protection.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 44

F50EEPROM failure.Critical

Description

EEPROM failure.

Cause

EEPROM failure.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 44

F51DSP1 communication failure.Critical

Description

DSP1 communication failure.

Cause

DSP1 communication failure.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 44

F52DSP2 communication failure.Critical

Description

DSP2 communication failure.

Cause

DSP2 communication failure.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 44

F53PV parallel failure.Fault

Description

PV parallel failure; PV1 and PV2 paralleling configuration mismatch.

Cause

PV1 and PV2 paralleling configuration mismatch.

Recommended fix

Please confirm whether PV1 and PV2 need to be set to parallel mode. if not, please turn off this function in APP. if necessary, please confirm whether the wiring of PV1 and PV2 is connected to parallel mode.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 44

F54Temperature sensor disconnected.Critical

Description

Temperature sensor disconnected.

Cause

Temperature sensor disconnected.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 44

F87Battery input circuit failure.Critical

Description

Battery input circuit failure.

Cause

Battery input circuit failure.

Recommended fix

Restart the unit, if the error persists, contact the repair center.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 44

W07Low battery.Warning

Description

Low battery warning shown on LCD with flashing error icon.

Cause

The battery voltage is too low.

Recommended fix

It should be charging.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 42

W09Overload.Warning

Description

Overload warning. Audible alarm: beep twice every second.

Recommended fix

Reduce the loads.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 42

W25Phase Sequence Errors.Warning

Description

Phase sequence error warning between input and output AC power lines.

Recommended fix

Check that the input and output power lines correspond.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 42

W51BMS doesn't allow inverter to discharge battery.Warning

Description

BMS does not allow the inverter to discharge battery; inverter will stop discharging battery automatically.

Cause

BMS doesn't allow inverter to discharge battery.

Recommended fix

Inverter will stop discharging battery automatically.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 42

W52BMS require inverter to charge battery.Warning

Description

BMS requires inverter to charge battery; inverter will charge battery automatically.

Cause

BMS require inverter to charge battery.

Recommended fix

Inverter will charge battery automatically.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 42

W60BMS firmware version is not matched.Warning

Description

BMS firmware version is not matched with the inverter.

Cause

BMS firmware version is not matched.

Recommended fix

Upgrade the firmware of BMS.

Source:Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf · page 42

Step-by-step troubleshooting checklist

1.Note the exact code and timing
Write down the exact code shown on the display, what the unit was doing when it appeared (charging, discharging, idle, grid-tied), and any LEDs or audible alarms. The same code can have different fixes depending on context.
2.Check the recommended fix on this page
Find the code in the list below and read the cause + recommended fix. Most warning-level codes can be cleared by following the listed action — usually reducing load, checking wiring, or restarting the unit.
3.Verify the source manual page
Each code shows the source manual filename and page number. Open that exact page in the official manual to verify model-specific notes (firmware version, parallel-config notes, regional variants) before acting.
4.Disconnect AC, DC, and battery before opening
If a fix requires opening the enclosure or accessing terminals, disconnect AC input, DC PV, and battery in that order. Wait at least 60 seconds for capacitors to discharge before touching any conductors.
5.Escalate critical codes to authorized service
Critical codes (short-circuit, IGBT failure, BMS hardware error) should not be cleared by end users. Note the code, model number, and source manual page, then contact an authorized service partner.

Common questions about Apollo-5KLP1G01-MX error codes

Where can I find the official Felicity Apollo-5KLP1G01-MX error code manual?: Each code on this page lists the official source manual filename and page number at the bottom. The manuals are published by Felicity on their website; we compile the codes here so you can search across all of them at once instead of opening each PDF.
Is the Apollo-5KLP1G01-MX the same as other Felicity models?: Some Felicity units share firmware across a family of variants — the same fault codes apply to multiple model numbers. Look at the "also covers" chips below the title to see which other model numbers this page applies to.
What's the most critical code on a Felicity Apollo-5KLP1G01-MX?: Critical-severity codes (red dot) are the ones that trip the unit offline immediately — typically short-circuit, IGBT, or BMS hardware failures. These are listed first when you filter by severity. Do not bypass them; they indicate a hardware or safety condition that requires service.