# INVT GD20 fault codes: OC1, OV2, ETH1 and what to check

INVT GD20 fault codes explained: what OC1 to OC3, OV1 to OV3, OUt1, OH1, OL1, SPI and ETH1 mean, which P07 fault records to copy before you reset, and what the manual says to check first, from braking settings to the motor cable. Every point cites a printed page of INVT's official manual.

**Short answer:** On an INVT Goodrive20 (GD20) drive, the fault code names the fault and, for overcurrent and overvoltage, when it tripped: OC1 and OV1 while accelerating, OC2 and OV2 while decelerating, OC3 and OV3 at constant speed. ETH1 and ETH2 are output-to-ground faults. Copy P07.27 to P07.56 before you reset.

**Applies to:** INVT Goodrive20 (GD20) series VFDs. The GD20-EU and GD20-UL versions and other INVT series, such as GD200A, GD100 and GD350, have their own manuals, and their codes and parameter numbers can differ, so check yours · **Manual used:** INVT Goodrive20 Series VFD Manual, V2.1 (PDF dated July 2025), downloaded from INVT's own GD20 product page. Page numbers below are the printed page numbers · **Last verified:** 30 Oct 2026 · **Author:** Muhammed Fahiz

## What does this look like on site?

A GD20 on a conveyor, fan or pump stops. The TRIP light on the keypad is on and the display is blinking OC1, OV2 or ETH1. The line is waiting, and the manual isn't in the panel door.

Search for INVT codes and much of what comes back is copied or translated from the manual, without page numbers. Jason (@JasonYu618), a drive repairer, posted on X in October 2026: "So I made a free fault code lookup: Inovance, Delta, INVT, Yaskawa, Mitsubishi, Fuji." Lookups like that are a good start. This page is the next step for the GD20: what each common code means, what INVT's own manual says to check, and the printed page, so you can confirm it on your copy. It doesn't reproduce INVT's tables.

## How do you read an INVT GD20 fault code?

The code is a short abbreviation, and for overcurrent, overvoltage and inverter-unit faults the number on the end matters. In the manual's fault table, each code also has a fault-type number in square brackets, the number you'd read over communication or in the fault records (p. 112).

| Code | Name in the manual | When it trips | Manual page (V2.1) |
|---|---|---|---|
| OUt1 / OUt2 / OUt3 | Inverter unit protection, U / V / W phase | One output phase of the power unit | p. 112 |
| OC1 / OC2 / OC3 | Overcurrent during acceleration / deceleration / constant speed | Ramping up / ramping down / at speed | p. 112 |
| OV1 / OV2 / OV3 | Overvoltage during acceleration / deceleration / constant speed | Ramping up / ramping down / at speed | pp. 112–113 |
| UV | Bus undervoltage | Supply too low | p. 113 |
| OL1 / OL2 | Motor overload / VFD overload | Load too heavy for motor or drive | p. 113 |
| SPI / SPO | Phase loss on input side / output side | Supply or motor side | p. 113 |
| OH1 / OH2 | Rectifier module overheat / inverter module overheat | Cooling | p. 113 |
| EF | External fault | An input set as external fault has acted | p. 113 |
| ItE | Current detection fault | Drive hardware | p. 114 |
| tE | Motor autotuning fault | During autotuning | p. 114 |
| bCE | Braking unit fault | Braking circuit | p. 114 |
| ETH1 / ETH2 | To-ground short-circuit fault 1 / 2 | Output to ground | pp. 115–116 |

*Our summary of section 6.2.3 of the GD20 manual V2.1. The full table runs from p. 112 to p. 116 and also covers CE, EEP, PIDE, END, OL3, PCE, UPE, DNE, dEu, STo and LL.*

For scale, the specification table rates the drive for 150% of rated current for 1 minute, 180% for 10 seconds and 200% for 1 second (p. 7).

On the keypad, the TRIP light is on when the drive is in fault and off when it's normal. If it's blinking, the drive is in a pre-alarm state and is about to trip (p. 25). When a fault is active, the code blinks on the display (p. 28).

## What should you write down before you press RESET?

Write down the last fault types and the drive's state at each one. The GD20 keeps them in group P07, and step 2 of the manual's fault procedure is to check those records to confirm the real state when the fault happened (p. 111).

- **Fault types:** P07.27 is the present fault, and P07.28 to P07.32 are the five before it, back to the "last but four" (pp. 73–74). Each holds a number from the manual's list: 4 for OC1, 8 for OV2, 32 for ETH1, and so on (p. 74).
- **Conditions at the present fault:** P07.33 to P07.40 hold the running frequency, ramp reference frequency, output voltage, output current, bus voltage, temperature and input and output terminal states (pp. 74–75).
- **The two before it:** P07.41 to P07.48 hold the same values for the last fault, and P07.49 to P07.56 for the one before that (pp. 75–76).

The output current and bus voltage at the trip are the numbers to copy into the job report with the code. They tell you whether an OC trip was a real current peak and how high the bus went on an OV trip, and they're gone once newer faults roll them out. Our post on [what to write before you close a breakdown job](https://hangersearch.com/blog/its-running-now-is-not-a-fix) covers the rest of that record. One thing not to do: P00.18 = 2 clears the fault records (pp. 37–38).

The manual lists three ways to reset: the STOP/RST key, a digital input, or switching the power off and on (p. 111). On the keypad, STOP/RST resets a fault in any control mode (P07.04, p. 71). For the terminal reset, function 7 is fault reset, and it's the default for terminal S3 (P05.03, p. 57). Auto reset is off by default: P08.28 (auto fault reset count) is 0, with a range of 0 to 10, and P08.29 sets the interval, default 1.0 s (p. 80).

## OUt1, OUt2, OUt3: is it the IGBT?

Possibly, but it's not the only cause listed. The manual gives the same causes for all three phases: acceleration too fast, an IGBT module fault, false trips caused by interference, a poor connection on the driving wires, and improper grounding (p. 112). Its fixes are to increase the acceleration time, change the power unit, check the driving wires, and find and remove the interference.

If it does look like the power stage, our post on [IGBT failure symptoms and the diode-mode test](https://hangersearch.com/blog/igbt-failure-symptoms-vfd) covers the terminal checks.

## OC1, OC2, OC3: what causes overcurrent on a GD20?

The manual lists one set of causes for all three: acceleration or deceleration too fast, a supply voltage that's too low, a VFD too small for the load, load transients or an abnormal load, a ground short or output phase loss, strong external interference, and "the overvoltage stall protection is not open" (p. 112). The fixes are a longer acceleration time, checking the supply, a larger VFD, checking the load for a short (to ground or between wires) and for rough rotation, checking the output configuration, checking for interference, and checking the related function codes.

Two things in that entry are worth reading carefully:

- **The stall-protection cause.** Overvoltage stall is a separate function (P11.03, p. 95). The functions that act on overcurrent are the current-limit settings: P11.05 (current limit action, default 0x01, always valid), P11.06 (current-limit level, default 160.0% of rated, range 50.0% to 200.0%) and P11.07 (frequency drop rate during current limit, default 10.00 Hz/s) (pp. 95–96). We'd check both groups, but the manual doesn't say which it means.
- **Deceleration.** The causes include deceleration that's too fast, but the only ramp fix listed is "increase the ACC time". For OC2, the deceleration time is the one to look at. Acceleration and deceleration time 1 are P00.11 and P00.12, 0.0 to 3600.0 s, with defaults that depend on the model (p. 35).

If the motor parameters have changed or the motor was swapped, autotuning is in P00.15: 1 is rotating autotuning, 2 and 3 are static (p. 37).

For the general method of splitting an overcurrent trip between motor, cable, load and drive, see our guide to [isolating a VFD overcurrent trip](https://hangersearch.com/blog/vfd-overcurrent-fault-causes).

## OV1, OV2, OV3: why does a GD20 trip on overvoltage?

An overvoltage trip means the DC bus went too high. The manual gives one set of causes for all three: abnormal input voltage, large energy feedback from the load, no braking components, and "braking energy is not open" (pp. 112–113). Its fixes are to check the input power, check whether the deceleration time is too short or the drive is starting a motor that's still rotating, add energy-consumption (braking) components, and check the related function codes.

Appendix C describes what's happening on OV2: a high-inertia load decelerating drives the motor as a generator, the energy goes back to the DC bus, and if the bus voltage passes a set level the drive reports overvoltage (p. 166).

What to check on a GD20:

- **Is braking hardware fitted?** The specification table says the braking unit is built in as standard up to 37 kW and optional from 45 to 110 kW (p. 8), with a "-B" in the model code for the built-in braking unit (p. 9). The resistor is always external and connects only to PB and (+) (pp. 166, 168).
- **Is braking switched on?** P08.37 enables energy-consumption braking and defaults to 0, disabled. P08.38 sets the braking threshold voltage: 380.0 V by default for the 220 V class and 700.0 V for the 380 V class (p. 82). The fault table doesn't name a parameter for "braking energy is not open", but P08.37 is the one that matches it.
- **Is the resistor right?** Don't use a resistance below the minimum in the selection table, because the drive doesn't protect against the overcurrent that causes. If braking is frequent (a braking ratio above 10%), pick a higher-power resistor (p. 167).
- **Is the motor already turning when it starts?** On a fan or anything that coasts, the speed tracking start modes, P01.00 = 2 or 3, track the motor's speed and direction before starting. The manual notes they're only available on drives of 4 kW and above (p. 38).

Overvoltage stall protection, P11.03, is on by default, and P11.04 sets its level: 130% of standard bus voltage for the 380 V class and 120% for the 220 V class (p. 95).

## ETH1 and ETH2: is it the motor, the cable or the drive?

ETH1 and ETH2 are "to-ground short-circuit" faults. The causes listed are an output shorted to ground, a fault in the current-detection circuit, and a large difference between the motor power set in the drive and the drive's own power (pp. 115–116). The fixes are to check the motor connection, change the Hall sensor, change the main control panel, and check that the motor power in group P2 matches the motor actually fitted.

The table entry runs across a page break, and the causes and fixes for ETH1 and ETH2 aren't clearly separated, so read them as one list. Start with the outside causes:

- **Motor and cable first.** If they're fine, check the motor power setting, then suspect the drive's current detection.
- **Wait before you open the drive.** Disconnect the power and wait for the time marked on the drive, or until the DC bus is below 36 V. The minimum is 5 minutes for the 220 V models up to 2.2 kW (single-phase) or 7.5 kW (three-phase) and the 380 V models from 0.75 to 110 kW (p. 2).
- **A wet motor reads low.** The manual notes that moisture inside the motor reduces insulation resistance, and says to dry it and measure again (p. 158).

The GD20 manual doesn't give an insulation-test procedure. The usual practice is to 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.

## OH1, OH2, OL1, OL2, SPI and SPO: overheating, overload and phase loss

- **OH1 (rectifier module) and OH2 (inverter module)** share three causes: a jammed air duct or damaged fan, ambient temperature too high, and overload running for too long. The fixes are to clear the duct or replace the fan and lower the ambient temperature (p. 113). The two module temperatures can be read in P07.11 and P07.12 (p. 73).
- **The fan has a life.** The manual gives the cooling fan a minimum life of 25,000 operating hours and says rising noise from the fan bearings warns that it's failing. The drive's running hours are in P07.14 (pp. 73, 109).

![Ink line drawing of a compact variable frequency drive on a workbench with its top cooling fan lifted out on its cable, exposing the heatsink fins, next to a soft brush and a replacement fan in an open box](/blog/media/invt-vfd-fault-codes-mvuhq24q.png)

- **OL1 (motor overload)** lists low supply voltage, the motor's rated current set wrongly, and a stall or strong load transients. The fixes are to check the supply, re-enter the motor's rated current and check the load and torque boost (p. 113).
- **OL2 (VFD overload)** lists acceleration too fast, restarting a motor that's still rotating, low supply voltage, a load that's too heavy, and a motor too big for the drive (p. 113).
- **SPI and SPO** are input and output phase loss (p. 113). The protection defaults depend on the drive size: on 2.2 kW and below, output phase loss protection is on and input phase loss is off; from 4 kW, input phase loss is also on (P11.00, p. 94). So a small GD20 may not trip SPI at all on a lost supply phase.

## What about ItE, tE and bCE?

- **ItE (current detection fault)** points to a poor contact on the control panel connector or a fault in the amplifier circuit. The fixes are to re-plug the connector or change the main control panel (p. 114).
- **tE (autotuning fault)** lists a motor that doesn't match the drive's capacity, wrong motor nameplate settings, autotuned values far from the standard ones, and autotuning timing out. Check the motor connection and nameplate data, take the load off for autotuning, and check that the upper limit frequency is above two-thirds of the rated frequency (p. 114).
- **bCE (braking unit fault)** is a braking circuit fault or damaged "braking pipes", as the manual puts it, or an external braking resistor that isn't sufficient. The fixes are to check the braking unit and replace the damaged part, or increase the braking resistor (p. 114).

## What should you check, in order?

1. **Copy P07.27 to P07.56.** **Expect:** the last six fault types, with output current and bus voltage at the last three. **If not:** if the present fault in P07.27 doesn't match the code on the display, note it before anyone resets again. (pp. 73–76, 111)
2. **Note the code and which phase it tripped in.** **Expect:** OC1/OV1 accelerating, OC2/OV2 decelerating, OC3/OV3 at constant speed. **If not:** for codes without a phase (ETH1, OUt1, OH1), go to that code's section above. (pp. 112–116)
3. **Power down and wait at least the time marked on the drive (5 minutes or more), then check the motor connection and test the motor and cable to ground with the motor cable disconnected at the drive.** **Expect:** good insulation and tight connections. **If not:** fix the motor or cable before powering up. (pp. 2, 115–116, 158)
4. **For overvoltage, check the supply, whether braking hardware is fitted, and P08.37.** **Expect:** supply in range, resistor on PB and (+), braking enabled. **If not:** fix that before touching ramp times. (pp. 8, 82, 112–113, 166–167)
5. **For overheating, check the fan, the air duct and the ambient temperature.** **Expect:** fan running quietly, duct clear. **If not:** clean the duct or replace the fan, and note P07.14. (pp. 109, 113)
6. **Only then look at ramp times, current limit, motor parameters, autotuning and speed tracking.** **Expect:** settings that suit the load. **If not:** change one at a time and record the old value. (pp. 35, 37–38, 95–96)
7. **If the fault returns with the motor and cable good, or the manual's fix is to change the power unit, Hall sensor or main control panel,** that's a drive repair. The manual says to contact the local INVT office if you can't find the cause (pp. 111–116).

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

| | Manual cause list | Field fixes reported |
|---|---|---|
| ETH1 / ETH2 | Output shorted to ground, current-detection fault, motor power setting far from drive power (pp. 115–116) | No field reports found yet. |
| OV2 | Abnormal input voltage, energy feedback, no braking components, braking not enabled (pp. 112–113) | No field reports found yet. |
| OC1 | Ramp too fast, low supply, drive too small, abnormal load, ground short or phase loss, interference, stall settings (p. 112) | No field reports found yet. |
| Source | INVT Goodrive20 Series VFD Manual V2.1 | None |
| Confidence | Official | None |

We looked for forum threads where someone reported fixing a specific GD20 code and confirmed it held. We didn't find any we could cite. What turns up for INVT codes mostly restates the manual's fault table. If you have a confirmed fix, it's worth writing it up with the code, the P07 records and what you replaced.

## Fault-code entry (summary block)

| Field | Value |
|---|---|
| Codes | OUt1–OUt3, OC1–OC3, OV1–OV3, UV, OL1, OL2, SPI, SPO, OH1, OH2, EF, ItE, tE, bCE, ETH1, ETH2 |
| Brand / series | INVT / Goodrive20 (GD20) |
| Official names | See the table under "How do you read an INVT GD20 fault code?" |
| Trips when | OC1/OV1 accelerating, OC2/OV2 decelerating, OC3/OV3 constant speed |
| Likely causes (ranked) | Overcurrent: ground short or phase loss, ramp time, abnormal load, drive too small, low supply, interference, limit settings. Overvoltage: energy from the load, no braking hardware or braking disabled (P08.37), ramp time, supply. ETH1/ETH2: motor and cable, motor power setting, then current detection |
| Checks in order | 1. Copy P07.27 to P07.56. 2. Note the code and phase. 3. Power down, wait, test motor and cable with the drive disconnected. 4. Supply and braking (overvoltage). 5. Fan and duct (overheat). 6. Settings. 7. Hardware causes = drive repair or INVT office |
| Field fixes reported | No field reports found yet |
| Related codes | TRIP light blinking = pre-alarm; OL3 and LL pre-alarms |
| Manual reference | INVT Goodrive20 Series VFD Manual V2.1, pp. 2, 7–9, 25, 28, 35, 37–38, 57, 71, 73–76, 80, 82, 94–96, 109, 111–116, 158, 166–168 |
| Last verified | 30 Oct 2026 |

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

Usually because the reset clears the trip, not the cause. If P08.28 has been set above its default of 0, the drive may already have reset itself several times, P08.29 seconds apart, before it stayed in the fault (p. 80). Compare the six fault types in P07.27 to P07.32 to see whether it's the same code each time.

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](https://hangersearch.com/blog/find-past-service-fix-repeat-machine-fault) covers where to look, and [the alarm someone already solved three years ago](https://hangersearch.com/blog/alarm-already-solved-three-years-ago) covers searching for it when the code was written down differently. For the same kind of breakdown on other brands, see our pages on [Inovance MD500 fault codes](https://hangersearch.com/blog/inovance-fault-codes), [Delta VFD fault codes](https://hangersearch.com/blog/delta-vfd-fault-codes) and [Siemens MM440 F0001](https://hangersearch.com/blog/siemens-mm440-f0001-fault-wont-reset).

## How would you find this in your own archive?

If your team has cleared ETH1 or OV2 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](https://hangersearch.com/trust).

Book a 20-minute demo: hangersearch.com

## FAQ

### What does OC1 mean on an INVT drive?
On an INVT GD20, OC1 is overcurrent during acceleration. The manual's causes include ramping too fast, a low supply voltage, a drive too small for the load, an abnormal load, a ground short or output phase loss, and interference (GD20 Manual V2.1, p. 112).

### What is ETH1 on an INVT GD20?
ETH1 is a to-ground short-circuit fault. Check the motor and cable to ground with the drive disconnected, then check that the motor power in group P2 matches the motor. If those are fine, the manual points to the current-detection hardware: the Hall sensor or the main control panel (pp. 115–116).

### How do I fix OV2 on an INVT inverter?
OV2 is overvoltage during deceleration, usually energy from the load as it slows. Lengthen the deceleration time, and check that a braking resistor is fitted on PB and (+) and that energy-consumption braking is enabled in P08.37, which is off by default (pp. 82, 112–113, 166).

### Where is the fault history on an INVT GD20?
In group P07. P07.27 is the present fault and P07.28 to P07.32 the five before it. P07.33 to P07.56 hold the frequency, current, bus voltage, temperature and terminal states at the last three faults (GD20 Manual V2.1, pp. 73–76).

### Why does the TRIP light blink without a fault code?
A blinking TRIP light means the drive is in a pre-alarm state and is about to trip. A steady TRIP light means it has tripped (p. 25).

## Sources

1. INVT, "Goodrive20 Series VFD Manual", V2.1 (PDF created 8 Jul 2025, 175 pages). Downloaded from INVT's website, linked as "GD20 Series VFD Manual" on the GD20 product page (https://www.invt.com/products/gd20-series-vfd-14): https://www.invt.com/uploads/file1/20250902/GD20%20VFD%20Manual_V2.1.pdf. Read 30 Oct 2026. Supports: safety wait (p. 2); specifications, overload rating, braking unit and model code (pp. 7–9); keypad indicators and fault display (pp. 25, 28); P00.11/P00.12 (p. 35); P00.15, P00.18 (pp. 37–38); P01.00 (p. 38); P05.03 (p. 57); P07.04 (p. 71); P07.11 to P07.14 (p. 73); P07.27 to P07.56 and the fault type list (pp. 73–76); P08.28/P08.29 (p. 80); P08.37/P08.38 (p. 82); P11.00 (p. 94); P11.03 to P11.07 (pp. 95–96); cooling fan (p. 109); fault indication, reset and procedure (p. 111); fault table (pp. 112–116); wet motor (p. 158); braking resistors (pp. 166–168). Printed page numbers (PDF page minus 5). Paraphrased.
2. Jason (@JasonYu618), post on X, 16 Oct 2026: https://x.com/JasonYu618/status/2111011466082201988. Read 30 Oct 2026. Supports: the "So I made a free fault code lookup: Inovance, Delta, INVT, Yaskawa, Mitsubishi, Fuji." quote.