Inovance MD500 fault codes: Err02, Err05, Err23 and what to check

Short answer: On an Inovance MD500 drive, the number after "Err" names the fault, and for overcurrent and overvoltage it also says when it tripped: Err02 and Err05 while accelerating, Err03 and Err06 while decelerating, Err04 and Err07 at constant speed. Err23 is a short to ground and only clears after a power-down. Copy F9-14 to F9-44 before resetting.

Applies to: Inovance MD500 series general-purpose AC drives. Other Inovance series, such as MD200, MD290, MD310 and MD520, have their own manuals, and their codes and parameter numbers can differ, so check yours · Manual used: Inovance MD500 Series AC Drive User Guide, data code 19010374, version A06 (March 2026), and MD500 Series General-Purpose AC Drive (Advanced) User Guide, data code 19010355, version B04, both downloaded from Inovance's own file server. Page numbers below are the printed page numbers · Last verified: 29 Oct 2026 · Author: Muhammed Fahiz

What does this look like on site?

An Inovance MD500 on a pump or fan panel stops, the fault indicator flashes and the display shows Err02, Err06 or Err23. The fault relay has dropped, the line is waiting, and nobody on shift has the manual for this drive.

Some of what turns up when you search for Inovance codes is translated. Jason (@JasonYu618), who wrote on X in October 2026 that he has "fixed VFDs and servo drives for about 20 years", built a free fault-code lookup that covers Inovance among other brands. His own note on it was: "Machine-translated, so check the manual too."

This page is that check, for the MD500. It summarises what each common code means, what the two official MD500 guides say to look at, and the printed page, so you can confirm it on your own copy. It doesn't reproduce Inovance's tables.

How do you read an Inovance MD500 fault code?

The display shows "Err" and a two-digit number. For overcurrent and overvoltage, the number itself tells you what the drive was doing, which narrows the cause before you open the panel.

Code	Name in the manual	When it trips	Manual page (UG A06)
Err02	Overcurrent during acceleration	Ramping up	p. 62
Err03	Overcurrent during deceleration	Ramping down	p. 63
Err04	Overcurrent at constant speed	At speed	p. 63
Err05	Overvoltage during acceleration	Ramping up	p. 64
Err06	Overvoltage during deceleration	Ramping down	p. 64
Err07	Overvoltage at constant speed	At speed	p. 64
Err08	Pre-charge power fault	Bus voltage hovering near the undervoltage level	p. 64
Err09	Undervoltage	DC bus too low	p. 65
Err10 / Err11	AC drive overload / Motor overload	Load too heavy for drive or motor	p. 65
Err12 / Err13	Input phase loss / Output phase loss	Supply or motor side	p. 65
Err14	IGBT overheat	Heatsink and cooling	p. 65
Err17	Contactor fault	Pre-charge relay or contactor	p. 66
Err18	Current detection fault	Drive hardware	p. 66
Err23	Short circuit to ground	Output to ground	p. 66
Err40	Pulse-by-pulse current limit fault	Heavy or locked load	p. 67
Err45	Motor overheat	Motor temperature sensor	p. 68
Err61 / Err62	Braking unit overload / Short-circuit of braking circuit	Braking circuit	p. 68

Our summary of section 6.1 of the MD500 User Guide A06. The full list runs from p. 62 to p. 68.

For scale, the user guide's specification table says the drive stops when the DC bus goes above 820 V or below 350 V, and when output current passes 250% of rated (instantaneous overcurrent). Its overload protection allows 150% of rated current for 60 seconds (pp. 16 and 21; the MD500T450G is rated 130% for 60 s). Those figures are for the three-phase 380–480 V models in that table.

Not every problem gets an Err code. Some faults can be set to keep running or to stop by the stop mode, and then the display shows A followed by the number (A11, A13 and so on) instead of Err. The advanced guide explains it: coast to stop shows Err**, stop by the stop mode shows A** and then Err** once stopped, and continue to run shows A** while the drive keeps going (Advanced UG, p. 160). The faults this applies to are set in F9-47 to F9-50 (pp. 159–160). If you see an A code, the drive is warning you about a fault it was told not to trip on.

What should you write down before you press RESET?

Write down the last three faults and the drive's state at each one. The MD500 keeps them in group F9, and the advanced guide's reset procedure tells you to check them first, before you remove the cause and reset (Advanced UG, p. 294).

• Fault types: F9-14 is the 1st fault, F9-15 the 2nd and F9-16 the 3rd, which is the latest. Each holds a number that matches the Err code: 2 for overcurrent during acceleration, 23 for short to ground, and so on (UG A06, p. 87).
• Conditions at the latest fault: F9-17 to F9-24 hold the frequency, current, bus voltage, DI and DO states, drive state, power-on time and running time at the 3rd (latest) fault (p. 87).
• The two before it: F9-27 to F9-34 hold the same values for the 2nd fault, and F9-37 to F9-44 for the 1st (pp. 87–88).

The current and bus voltage at the trip are the numbers you want. For overcurrent codes, the manual's last line on Err02, Err03 and Err04 is to look at the historical fault records: if the recorded current is far below the overcurrent level, look for an interference source, and if there isn't one, the driver board or Hall element may be faulty (pp. 62–63). That check is impossible once the record has rolled over. Copy the values into the job report with the code. Our post on what to write before you close a breakdown job covers the rest of that record.

The ways to reset are a DI terminal set to function 9, the STOP/RES key (it works in any control mode when F7-02 = 1, the default), switching off until the display clears and switching on again, or a host writing 7 to address 2000H when F0-02 = 2 (Advanced UG, p. 294; F7-02 on UG p. 83). Two exceptions: Err09 resets by itself when the bus voltage recovers and doesn't count towards F9-09's auto-reset limit, and Err23 can't be reset automatically or manually, only by powering down (Advanced UG, p. 159).

Err02, Err03, Err04: what causes overcurrent on an MD500?

The user guide lists the same core causes for all three and then adds the ones that depend on when it tripped (pp. 62–63). The shared ones are a ground fault or short in the output circuit (check the motor, the motor cable and any contactor), sensorless or closed-loop vector control (SVC or FVC) running without a motor auto-tune, stall-prevention settings, and external interference.

Code	Causes specific to this phase (manual)	Pages
Err02	Acceleration time too short; torque boost or V/F curve not suited to the load; motor started while still spinning	p. 62
Err03	Deceleration time too short; no braking unit and resistor fitted	p. 63
Err04	Drive too small for the load (output current above the motor's or drive's rating in steady running)	p. 63

The stall-prevention advice is the same on all three entries: make sure current limit is on (F3-19 = 1), keep F3-18 (current limit level) between 120% and 150%, and keep F3-20 (current limit gain) between 20 and 40 (pp. 62–63). In the parameter table, F3-18 defaults to 150%, F3-19 to enabled and F3-20 to 20 (pp. 78–79).

The spinning-motor cause matters on fans. A fan that's windmilling in a draught, or still coasting after a stop, is already turning when the drive starts it. The manual's fix is to enable the flying start function or wait for the motor to stop (p. 62). On the MD500 that's F6-00 = 1, "catching a spinning motor", and the advanced guide notes that it relies on the motor parameters in group F1 being set correctly (UG A06, p. 82; Advanced UG, p. 137).

The advanced guide's Err03 entry lists "acceleration time is too short" where the user guide says deceleration time (Advanced UG, p. 295; UG A06, p. 63). For a trip during deceleration, the user guide's wording is the one that makes sense, but it's worth knowing the two copies differ if you're reading the advanced guide on site.

For the general method of splitting an overcurrent trip between motor, cable, load and drive, see our guide to isolating a VFD overcurrent trip. If the short turns out to be inside the drive, our post on IGBT failure symptoms and the diode-mode test covers the terminal checks.

Err05, Err06, Err07: why does an MD500 trip on overvoltage?

An overvoltage trip means the DC bus went too high. The user guide gives the same three families of cause for all three codes: input voltage too high, an external force driving the motor (regeneration), and voltage-limit settings (p. 64).

• Err06 (deceleration) is the common one: the load is driving the motor as it slows. The manual's options are a longer deceleration time, a braking unit and braking resistor, or removing the external force (p. 64).
• Err05 (acceleration) adds an acceleration time that's too short and a missing braking unit and resistor (p. 64).
• Err07 (constant speed) points to an external force at speed, and adds one more setting: F3-26 (frequency rise threshold during voltage limit), which the manual suggests setting between 5 Hz and 20 Hz (p. 64).

On all three, the manual's voltage-limit advice is to make sure the voltage limit is on (F3-23 = 1), keep F3-22 (voltage limit) between 700 V and 770 V, and keep F3-24 (frequency gain for voltage limit) between 30 and 50 (p. 64). F3-22 defaults to 770.0 V in the A06 parameter table (p. 79).

There's a catch if the drive has a braking resistor or braking unit. The advanced guide's note on the voltage limit says that when one is fitted, you should set F3-23 to 0 (disabled), otherwise the deceleration time may become longer, and set F3-10 (V/F over-excitation gain) to 0, otherwise the current may be too high (Advanced UG, p. 151). So "ensure F3-23 = 1" in the fault table is advice for a drive without braking hardware. Check which you have before changing it.

Err09 and Err08: is low voltage always the supply?

Mostly, yes. The user guide's causes for Err09 are a momentary power failure, input voltage outside the permitted range, an abnormal bus voltage, and faults in the rectifier bridge, pre-charge resistor, driver board or control board (p. 65). For momentary dips, it says to enable power dip ride-through (F9-59 ≠ 0; the default is 0, disabled, p. 89). For the hardware causes, it says to contact the agent or Inovance.

Err08 (pre-charge power fault) is listed with a single cause: the bus voltage keeps fluctuating around the undervoltage threshold. The manual's action is to contact the agent or Inovance (p. 64).

Err23: is it the motor, the cable or the drive?

Err23 means the drive found a short circuit to ground on its output. The fault table's cause is the motor shorted to ground, and its fix is to replace the cable or the motor (p. 66). The symptoms table adds the order to work in when Err23 shows at power-on: check the insulation of the motor and the output cable with a megger, and if those are good, the drive itself may be damaged, so contact the agent or Inovance (p. 69).

Three details from the manuals:

• It's checked at power-on by default. F9-07 controls short-to-ground detection. Its default, 01, enables the check at power-on and leaves the check before each run disabled (UG A06, p. 86).
• It won't clear by reset. Err23 can't be reset automatically or manually. It only clears after power-down (Advanced UG, p. 159).
• Wait before you open the drive. The user guide says to cut off all power and wait at least 10 minutes before maintenance (p. 8).

For the megger test itself, disconnect the motor cable at the drive so the test voltage doesn't reach the drive's output, then test the motor and cable to ground.

Err13, Err12 and Err14: what about phase loss and overheating?

• Err13 (output phase loss) points to an open circuit in the motor, a problem in the cable between drive and motor, unbalanced output while running (check the motor windings), or the driver board or IGBTs (p. 65). By default, output phase loss is checked while running but not before running (F9-13 = 01, p. 87). The advanced guide adds a warning: if you turn the check off and a phase does go missing, the drive won't detect it, and the actual current is higher than the current on the display. It also says the before-run check takes several seconds, so it suits low-frequency applications and those where starting on a missing phase is a risk (Advanced UG, p. 158).
• Err12 (input phase loss) is a missing supply phase, or a fault in the driver board, lightning protection board, main control board or rectifier bridge (p. 65).
• Err14 (IGBT overheat) lists high ambient temperature, blocked ventilation, a damaged fan, a damaged IGBT thermistor and a damaged IGBT (p. 65). If it happens often, the symptoms table says to replace the cooling fan and clean the ventilation (p. 69). A related symptom: if the display is normal at power-on but shows "HC" and stops as soon as the drive runs, the causes include a damaged or stopped cooling fan, a short on the external control terminal cable, or a carrier frequency that's too high, in which case reduce F0-15 (p. 69).

What about Err17, Err45 and Err61/62?

• Err17 (contactor fault) lists the driver board and power supply, the contactor and the lightning protection board (p. 66). The advanced guide's symptoms table covers Err17 at power-on or while running: the pre-charge relay or contactor isn't closing, so check its cable, the relay or contactor itself, and the 24 V supply to the contactor (Advanced UG, p. 303).
• Err45 (motor overheat) comes from the motor temperature sensor input. The causes are a loose sensor cable or a motor that really is too hot (p. 68). The two guides disagree on carrier frequency here: the user guide says to increase it (p. 68), the advanced guide says to decrease it (Advanced UG, p. 301). We'd check with Inovance before changing F0-15 for this reason. The sensor type is set in F9-56 (PT100 or PT1000), and the advanced guide notes the temperature can be read in U0-34 (Advanced UG, p. 161).
• Err61 (braking unit overload) means the braking resistor's resistance is too small, and the fix is a resistor of larger resistance. Err62 (short-circuit of braking circuit) points to the braking module, and the action is to contact the agent or Inovance (p. 68).

What should you check, in order?

1. Copy F9-14 to F9-44. Expect: the last three fault types, with current and bus voltage at each. If not: if the latest record doesn't match the code on the display, note it before anyone resets again. (UG A06, pp. 87–88; Advanced UG, p. 294)
2. Note whether it's Err or A, and which phase it tripped in. Expect: Err02/05 accelerating, Err03/06 decelerating, Err04/07 at constant speed. If not: for codes without a phase (Err23, Err13, Err14), go to that code's section above. (pp. 62–68; Advanced UG, p. 160)
3. For overcurrent, compare the recorded current with the overcurrent level. Expect: close to the level, pointing at the load, ramp or wiring. If not: if it's far below, the manual says look for interference, then the driver board or Hall element. (pp. 62–63)
4. Power down, wait at least 10 minutes, disconnect the motor cable at the drive and megger the motor and cable to ground. Expect: good insulation. If not: replace the cable or motor before powering up. (pp. 8, 66, 69)
5. For overvoltage, check the supply voltage, the braking unit and resistor, and what's driving the motor. Expect: supply in range, braking hardware fitted and wired. If not: fix that before touching the voltage-limit settings, and check F3-23 against whether braking hardware is fitted. (p. 64; Advanced UG, p. 151)
6. Only then look at ramp times, current and voltage limits, auto-tuning and flying start. Expect: settings suited to the load. If not: change one at a time and record the old value. (pp. 62–64, 78–79, 82)
7. If Err23 returns after power-down with the motor and cable tested good, or Err18, Err62 or a hardware cause is listed, the manual's action is to contact the agent or Inovance. (pp. 66, 68–69)

What does the manual say vs what has fixed it in the field?

	Manual cause list	Field fixes reported
Err23	Motor or motor cable shorted to ground, then drive damage (pp. 66, 69)	No field reports found yet.
Err06	Deceleration too short, external force, no braking hardware, voltage-limit settings (p. 64)	No field reports found yet.
Err02	Output short, no auto-tune, acceleration too short, current limit, V/F curve, spinning motor, interference (p. 62)	No field reports found yet.
Source	Inovance MD500 User Guide A06 and Advanced User Guide B04	None
Confidence	Official	None

We looked for forum threads where someone reported fixing a specific MD500 code and confirmed it held. We didn't find any we could cite. What search turns up for Inovance codes mostly restates the manual, often in translation. If you have a confirmed fix, it's worth writing it up with the code, the F9 records and what you replaced.

Fault-code entry (summary block)

Field	Value
Codes	Err02–Err07, Err08, Err09, Err10–Err14, Err17, Err18, Err23, Err40, Err45, Err61, Err62
Brand / series	Inovance / MD500
Official names	See the table under "How do you read an Inovance MD500 fault code?"
Trips when	Err02/05 accelerating, Err03/06 decelerating, Err04/07 constant speed; Err23 checked at power-on by default (F9-07)
Likely causes (ranked)	Overcurrent: output short or ground fault, missing auto-tune, ramp time, current-limit settings, spinning motor, interference or hardware. Overvoltage: regeneration, no braking hardware, ramp time, supply, voltage-limit settings. Err23: motor, cable, then drive
Checks in order	1. Copy F9-14 to F9-44. 2. Note Err vs A and the phase. 3. Compare recorded current with the trip level. 4. Megger motor and cable with the drive disconnected. 5. Supply and braking hardware (overvoltage). 6. Settings. 7. Hardware causes = contact agent or Inovance
Field fixes reported	No field reports found yet
Related codes	A** alarms (same numbers, set by F9-47 to F9-50), "HC" display at power-on or run
Manual reference	Inovance MD500 User Guide 19010374 A06, pp. 8, 16, 21, 62–69, 78–79, 82–83, 86–89; MD500 Advanced User Guide 19010355 B04, pp. 137, 151, 158–161, 294–295, 301, 303
Last verified	29 Oct 2026

Why does the same Inovance code keep coming back after a reset?

Usually because the reset clears the trip, not the cause. If F9-09 (auto reset times) is set above its default of 0, the drive may already have reset itself a few times, waiting F9-11 (default 1.0 s) each time, before it stays in the fault (Advanced UG, p. 159; UG A06, pp. 86–87). Compare the power-on and running times in the three F9 records to see how close together the repeats were.

If this drive has tripped on the same code before, someone may already have found the cause. Our guide on finding a past service fix for a repeat machine fault covers where to look, and the alarm someone already solved three years ago covers searching for it when the code was written down differently. For the same kind of breakdown on another brand, see our pages on Delta VFD fault codes and Siemens MM440 F0001.

How would you find this in your own archive?

If your team has cleared Err23 on this drive before, the cause is probably in a service report somewhere. HangerSearch searches your own finalized reports, shows the few prior cases that match and why each matched, and opens the cited page. Every result points to a real report from your own archive. Nothing is generated, and if there's no match it says so. See how we handle your reports.

Book a 20-minute demo: hangersearch.com

FAQ

What does Err02 mean on an Inovance drive?

On an Inovance MD500, Err02 is overcurrent during acceleration. The user guide's causes include a short or ground fault in the output circuit, no motor auto-tune in SVC or FVC mode, an acceleration time that's too short, current-limit settings, an unsuitable V/F curve, starting a motor that's still spinning, and interference (MD500 User Guide A06, p. 62).

What is Err23 on an Inovance MD500?

Err23 is a short circuit to ground on the drive's output. Megger the motor and output cable with the drive disconnected. If they're good, the drive may be damaged. Err23 can't be reset by the STOP/RES key or auto-reset; it clears only after power-down (User Guide A06, pp. 66, 69; Advanced User Guide, p. 159).

How do I fix Err06 on an Inovance inverter?

Err06 is overvoltage during deceleration, usually energy from the load as it slows. The manual's options are a longer deceleration time, a braking unit and resistor, removing the external force, and voltage-limit settings (F3-22 to F3-24). If braking hardware is fitted, the advanced guide says to disable the voltage limit (F3-23 = 0) (pp. 64; Advanced UG, p. 151).

Where is the fault history on an Inovance MD500?

In group F9. F9-14, F9-15 and F9-16 hold the last three fault types, with F9-16 the latest. F9-17 to F9-24, F9-27 to F9-34 and F9-37 to F9-44 hold the frequency, current, bus voltage, terminal states and times at each of those faults (MD500 User Guide A06, pp. 87–88).

What does an "A" code like A13 mean instead of Err13?

It means the fault's protection action is set to "stop according to the stop mode" or "continue to run" in F9-47 to F9-50, so the drive shows a warning rather than tripping straight away. With "stop according to the stop mode" it shows A** while stopping and Err** once stopped (Advanced User Guide, pp. 159–160).

Sources

1. Inovance Technology, "MD500 Series AC Drive User Guide", data code 19010374, version A06 (March 2026; PDF created 26 Mar 2026, 106 pages). Downloaded from Inovance's file server: https://portal-file.inovance.com/owfile/ProdDoc/SC/19010374-SC/A06/19010374-SC_A06_MD500%20Series%20AC%20Drive%20User%20Guide_EN.pdf. Read 29 Oct 2026. Supports: safety wait (p. 8); specifications and protections (pp. 16, 21); fault codes Err02 to Err62 (pp. 62–68); symptoms, including Err23 and HC at power-on, HC after run and frequent Err14 (pp. 68–69); F3-18 to F3-26 (pp. 78–79); F6-00 (p. 82); F7-02 (p. 83); F9-07 to F9-09 (p. 86); F9-11 to F9-28 and the fault type list (p. 87); F9-29 to F9-44 (p. 88); F9-59 (p. 89). Printed page numbers (PDF page minus 1). Paraphrased.
2. Inovance Technology, "MD500 Series General-Purpose AC Drive User Guide" (Advanced), data code 19010355, version B04 (PDF dated 8 Jan 2022). Downloaded from Inovance's file server: https://portal-file.inovance.com/owfile/ProdDoc/SC/19010355-SC/B04/19010355-SC_B04%E3%80%8AMD500%20Series%20General-Purpose%20AC%20Drive%20User%20Guide%E3%80%8B-EN20220107.pdf. Read 29 Oct 2026. Supports: catching a spinning motor (p. 137); voltage limit and braking note (p. 151); F9-12/F9-13 phase loss (p. 158); fault reset, Err09 and Err23 reset rules, F9-47/F9-48 (p. 159); A** and Err** display by protection action, F9-49/F9-50 (p. 160); motor temperature sensor (p. 161); fault display and reset methods (pp. 293–294); Err03 entry (p. 295); Err45 entry (p. 301); frequent overcurrent and overvoltage, Err17 at power-on (p. 303). Printed page numbers. Paraphrased.
3. Jason (@JasonYu618), post on X, 16 Oct 2026: https://x.com/JasonYu618/status/2111011466082201988. Read 29 Oct 2026. Supports: the "fixed VFDs and servo drives for about 20 years" and "Machine-translated, so check the manual too" quotes, and that his lookup covers Inovance.