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The “big five” most common Dexter washer faults and how to fix them.

Written by jd

Nov 25, 2025

(615) 885-1115

Here are the Dexter washer error codes you’ll run into the most in the field (T-series / WCVD / O-Series / Express controls), what they mean, and the quickest way to diagnose/fix them. These come straight from Dexter’s common washer fault code guide. Dexter Laundry+5Dexter Laundry+5Dexter Laundry+5

The “big five” most common Dexter washer faults

F1 — Door Lock Error (DOOR LOCK ERROR)

Meaning: Door didn’t close/lock, or lock signal dropped during the cycle. Dexter Laundry
Typical causes

  • Door not aligned / striker worn / hinge sag

  • Lock solenoid/thermo-actuator weak

  • Lock switch or harness issue (often at hinge)

Fix / diagnosis

  1. Mechanical first: Confirm door is closing square and striker fully enters lock.

  2. Listen for lock engagement at start.

  3. Power off, check wiring to door/lock switches and controller (Dexter calls out P-4). Dexter Laundry

  4. Meter lock coil & lock switches. If coil open/short or switch doesn’t change state → replace lock.

F2 — Slow Fill Error (SLOW FILL ERROR)

Meaning: Washer didn’t reach low level within 7 minutes. Cycle may continue but code flashes. Dexter Laundry
Typical causes

  • Supply valves partially closed / low building pressure

  • Inlet screens clogged

  • Fill valve coil failed

  • Drain valve leaking open (water in but level won’t rise)

Fix / diagnosis

  1. Verify hot/cold wall valves fully open; confirm pressure/flow.

  2. Remove hoses and clean inlet screens in valve body. Dexter Laundry

  3. In diagnostics, command hot then cold fill; if no actuation, check coil resistance and voltage to valve.

  4. If water enters but level doesn’t rise, check for drain valve stuck open or obstruction. Dexter Laundry

F8 — Slow Drain / Drain Error (SLOW DRAIN ERROR)

Meaning: Empty level not reached within 7 minutes. Dexter Laundry
Typical causes

  • Coin trap/sump or pump inlet clogged

  • Drain hose kinked or standpipe restricted/backing up

  • Weak drain pump

  • Pressure switch tube plugged so control thinks water remains

Fix / diagnosis

  1. Run drain test — you should see strong steady flow at the standpipe.

  2. Clean coin trap/sump and check impeller for debris.

  3. Verify hose routing and standpipe height/flow.

  4. Dexter specifically recommends checking that the pressure switch tube is clear and harness intact. Dexter Laundry

  5. If pump has correct voltage but weak/no flow → replace pump.

F3 — Memory / Checksum Error (MEMORY ERROR)

Meaning: Controller checksum wrong or parameter out of range. Dexter Laundry
Typical causes

  • Glitch/corruption in PCB

  • Failing controller

Fix / diagnosis

  1. Check VFD fault light before cycling power (Dexter warning). Dexter Laundry

  2. Try a soft reset using the white reset button. Dexter Laundry

  3. If it returns → replace PCB controller.

F4 / F5 / F6 / F7 — Communication / Configuration faults

These show up less than the top three, but still common after board swaps or harness issues.

  • F4 — COMM ERROR 1 (I2C bus error)
    Meaning: Internal comm error in controller. Dexter Laundry
    Fix: Check/replace data cable, remove tension, verify connectors P23↔P15; if persistent, replace PCB. Dexter Laundry

  • F5 — COMM ERROR 2 (Wrong washer size jumper config)
    Meaning: Size/type harness mismatch. Often after wrong controller install. Dexter Laundry
    Fix: Verify correct size/type harness and pressure switch harness; soft reset if corrected. Dexter Laundry

  • F6 / F7 — COMM ERROR 3 (Size/type changed)
    Meaning: Control detected different size/type input. Dexter Laundry
    Fix: Reseat harnesses, confirm correct VFD horsepower for washer size, soft reset. Dexter Laundry

  • F13 — COMM ERROR 4 (No VFD / VFD comm fault)
    Meaning: Controller can’t communicate with drive. Dexter Laundry
    Fix: Reseat/replace comm cable between PCB and VFD, inspect connectors; if still dead, suspect VFD. Dexter Laundry

Drive/VFD faults you’ll see a lot (especially on high-use stores)

These fault at the VFD and then present on the front as “drive” errors. They’re common in older installs, bad power, or mechanical drag.

F14 — DRIVE OC (VFD Over-Current)

Meaning: Drive sensed over-current. Dexter Laundry
Typical causes

  • Tub/bearings binding, foreign object, seized motor

  • Motor lead short or damaged

  • Braking resistor out of spec

Fix / diagnosis

  1. Turn tub by hand; if stiff, remove belt and isolate motor vs. tub drag.

  2. Inspect motor leads for touching/shorting; repair or replace. Dexter Laundry

  3. Measure braking resistor(s); replace if out of spec. Dexter Laundry

F15 — DRIVE OV (VFD Over-Voltage)

Meaning: DC bus too high. Dexter Laundry
Typical causes

  • Incoming voltage too high / “high-leg” wild power

  • Loose line lugs or braking resistor wiring

Fix / diagnosis

  1. Measure supply voltage at VFD L1/L2/L3; confirm within spec. Dexter Laundry

  2. Tighten line and braking-resistor terminals; verify resistor values. Dexter Laundry

  3. If high-leg power, Dexter notes disconnecting high leg or adding filtering/choke/suppressor. Dexter Laundry

F16 — DRIVE OH (VFD Overheat)

Meaning: VFD heatsink too hot. Dexter Laundry
Fix

  • Clean cooling fins/vents; verify VFD cooling fan runs during tumble/spin. Dexter Laundry

F17 — DRIVE OL (VFD Overload)

Meaning: Prolonged overload. Dexter Laundry
Typical causes

  • Mechanical drag

  • Loose/burned motor connections

  • Belt too tight/too loose

  • Braking resistor issue

Fix

  • Check motor spins freely, wiring tight, belt tension to ~1″ deflection at center, resistor values OK. Dexter Laundry

F18 — DRIVE GFI (Ground Fault)

Meaning: Drive sees ground fault. Dexter Laundry
Fix

  • Inspect motor and drive wiring to ground, confirm solid earth ground, look for damaged motor leads. Dexter Laundry

F19 — DRIVE LV (Low Voltage)

Meaning: Supply voltage low at drive. Dexter Laundry
Fix

  • Measure incoming line voltage under load; tighten terminals; check building circuit sizing. Dexter Laundry

A fast universal Dexter diagnostic flow

  1. Read the family:

    • F1 door/lock, F2 fill/level, F8 drain/level, F3 memory, F-drive = power/drive/mechanical.

  2. Check the obvious cheap stuff first: valves/screens, filters/coin trap, door alignment, hose kinks, supply voltage.

  3. Run component tests in service mode: fill, drain, lock, tumble/spin. If it won’t actuate there, it won’t in a cycle.

  4. Voltage-at-load rule:

    • Voltage present but no action → component.

    • No voltage → board/relay/harness/safety chain.

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