Dexter Washer Error Code F20: Internal Drive Error
F20 means an internal drive error. Read the drive code before power off, turn power off for one minute, and turn it on. If the problem comes back, contact your Dexter representative.
High: the drive reports an internal error, and the washer is down until it clears or is replaced.
What does Dexter error code F20 mean?
The drive runs its own internal checks, and when one of them fails it reports an internal error. The washer shows it as F20. The manual's instruction is short. Check the VFD code before the power goes off, since it is the only way to learn what the drive recorded. Then turn the power off, wait one minute and turn it back on. If the problem appears again, contact your Dexter representative. The manual lists no individual causes, so it expects a reset to clear a one-time event and a repeat to need service. Numbering depends on the washer generation. On the Dexter Common Washer guide, an internal drive error is F21, not F20, and F20 here applies only to the F-code generation of the T-450 SWD and WCAD manuals.
Affected models and control systems
Dexter T-450 SWD Express stack washer-dryers, serial 481983 and up. The same F10 to F21 table appears in the WCAD-Series vended washers manual (8533-073-001, 11/11). Older Dexter washers number their drive codes differently.
Code numbers and their meaning can change between control generations. We match the full model and control before acting on a code.
What you may notice
- F20 on the display
- Washer stops at the start of a cycle
- Drive lights showing a code
Possible causes
Likely causes — what usually sits behind error code F20 on this control. A technician confirms which one it is before any part is replaced.
- Power disturbance that corrupted the drive's memory
- Drive board overheated in a closed enclosure
- Surge from lightning or nearby heavy equipment
Safe checks before calling for service
- If you can wait, note the drive light code before you switch off.
- Turn the power off, wait one minute, then turn it on.
- Run a short cycle and see whether F20 returns.
- If it returns, tell the technician the drive code and when it appeared.
How a technician diagnoses error code F20
- Read the VFD code before power off.
- Power cycle for one minute and retest.
- Check the supply voltage and grounds for disturbances.
- Check the drive for heat and lint.
- Replace the drive if the internal error repeats.
- The drive is on a high-voltage supply and stores charge.
- Replacing a drive needs the right model and settings for the washer.
- Reading drive codes needs the manual's code table.
How error code F20 differs from similar codes
Dexter F-code generation only. The Common Washer guide, which labels alarms such as DRIVE OC and DRIVE OV, uses F6 for drive size mismatch, F9 for spin stop and F21 for an internal drive error.
Technical reference
- Maker documentation
- Dexter owner support
- Edition
- Part # 8533-070-001 (12/13), starting serial number 481983
- Models / control
- Dexter C-Series and T-series coin washers with VFD (T-300 to T-1450)
- Section
- Troubleshooting Washer Fault Errors (F-Codes), p.6-10
- Checked
- October 2026
We use the maker's document to read the code and do not reproduce it. Always confirm the complete model and control before applying these steps.
Related Dexter washer error codes
Will a power cycle clear F20?
The manual says to try one minute off, then on. If it returns, call.
Is F20 the same as F21?
No. F21 is the communications error in this generation.
What should I tell the technician?
The drive light code and whether it returned.
Need help with Dexter error code F20?
A technician confirms the cause on site and gives you the price in writing before any work starts.