Dexter Washer Error Code F21: Drive Communication Error (CExx)
F21 with CExx on the drive display means a data error on communications between the controller and the drive. Read the drive code, check the data cable, and wait 3 minutes before cycling main power.
Medium: communication is lost, but the usual cause is a cable and is quick to check.
What does Dexter error code F21 mean?
The controller and the drive talk to each other over a data cable. If messages are corrupted or missing, the drive reports internal drive error 32 and the washer shows F21, while the drive display shows a CE number. CE errors are communications errors and are often caused by noise on the data cable. This applies to the F-code generation, the T-450 SWD and WCAD manuals. On the Dexter Common Washer guide, which uses DRIVE labels, F21 is a different alarm for an internal drive error, so the DRIVE IF label does not apply here. The manual says to check the drive code before power off, check the data cable between the controller and the drive and replace it if it is damaged, and not to cycle the main power off and on too quickly, since the drive needs 3 minutes to reset. The causes are data cable noise and power cycled too quickly.
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
- F21 on the display
- CExx on the drive display
- Washer stops with no motor alarm
Possible causes
Listed in Dexter's documentation
- Data cable noise
- Power cycled too quickly
Other likely causes — what usually sits behind error code F21 on this control. A technician confirms which one it is before any part is replaced.
- Data cable routed beside the motor leads and picking up noise
- Cable connector loose at the drive
- Cable insulation cut where it passes a panel edge
Safe checks before calling for service
- Wait 3 minutes after switching off before you restart.
- Do not flick the power on and off repeatedly.
- Write down the CE number shown on the drive display.
- Call for service if F21 returns.
How a technician diagnoses error code F21
- Read the CE number on the drive display before power off.
- Inspect the data cable between the controller and the drive.
- Replace the cable if damaged.
- Check cable routing away from motor leads.
- Wait 3 minutes between power cycles during testing.
- The data cable connects live control and drive boards.
- Cable routing and shielding must be correct to avoid noise.
- Cycling power too quickly can confuse the drive.
How error code F21 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
What does CE mean?
It is a communications error code on the drive display.
Is the drive bad?
Usually not. Cable noise is the typical cause.
Is F21 always the same?
No. On the Common Washer guide it is an internal drive error.
Need help with Dexter error code F21?
A technician confirms the cause on site and gives you the price in writing before any work starts.