🌀Dryer

E:21

Bosch · WTG86401UC 4.0 cu ft 300 Series Condensation Dryer

Bosch WTG86401UC 4.0 cu ft 300 Series Condensation Dryer E:21 Error Fix: Control Module — Software Error

The control module has detected a software or firmware error. Disconnect power for 5 minutes and restore to attempt a reset. If the error code returns immediately, the electronic control board has an internal fault and must be replaced. Check for signs of power surges or electrical damage.

High severity2 fixes available✨ Free fix available

Quick Answer

Error E:21 on the Bosch WTG86401UC 4.0 cu ft 300 Series Condensation Dryer means: Control Module — Software Error. The top-ranked community fix is “Replace Electronic Control Board” (hard difficulty, ~60 min, DIY cost: $20-$30). 2 community-ranked fixes available below.

Published February 2026 · 2 fixes · dryer

Content is based on manufacturer service documentation, community repair experience, and OEM technical bulletins. Always verify with your owner's manual.Learn about our editorial standards.

When to Call a Professional

While many dryer repairs can be done safely at home, consider hiring a qualified technician if:

This is a high severity error — continued use may cause damage or a safety hazard
The repair involves electrical wiring, gas lines, or refrigerant
You've tried the top-ranked fix and the error persists
You smell gas, see sparking, or notice water leaking
The repair requires specialized tools you don't have
Your appliance is still under manufacturer warranty

Average professional repair cost for this issue: $250-$400.

Other Bosch Models with Error E:21

WTG865H4UC 4.0 cu ft 800 Series Condensation Dryer

dryer · 2 fixes

WTW87NH1UC 4.0 cu ft 800 Series Heat Pump Dryer

dryer · 2 fixes

WTW87NH2UC 4.0 cu ft 800 Series Smart Heat Pump

dryer · 2 fixes

Other Bosch WTG86401UC 4.0 cu ft 300 Series Condensation Dryer Error Codes

E:01

Restricted Exhaust Vent

2 fixes

E:03

Maximum Drying Time Exceeded

2 fixes

E:04

Heater Relay Stuck Open

2 fixes

E:07

Drum Motor Not Rotating

2 fixes

E:11

Restricted Exhaust — Secondary Alert

2 fixes

E:12

Restricted Exhaust — Tertiary Alert

2 fixes

E:13

Maximum Drying Time Exceeded — Repeated

2 fixes

E:17

Lint Screen Temperature Sensor Error

2 fixes

People Also Ask About Bosch WTG86401UC 4.0 cu ft 300 Series Condensation Dryer Error E:21

What does error code E:21 mean on a Bosch WTG86401UC 4.0 cu ft 300 Series Condensation Dryer?

Error code E:21 on the Bosch WTG86401UC 4.0 cu ft 300 Series Condensation Dryer means: Control Module — Software Error. The control module has detected a software or firmware error. Disconnect power for 5 minutes and restore to attempt a reset. If the error code returns immediately, the electronic control board has an internal fault and must be replaced. Check for signs of power surges or electrical damage.

How do I fix error code E:21 on my Bosch WTG86401UC 4.0 cu ft 300 Series Condensation Dryer?

The most successful fix is "Replace Electronic Control Board" (hard difficulty, ~60 minutes). Estimated DIY cost: $20-$30. HomeMD has 2 community-ranked fixes for this error.

Is error code E:21 on a Bosch WTG86401UC 4.0 cu ft 300 Series Condensation Dryer serious?

This error is rated high severity. You should address it promptly — continued use could cause damage or safety concerns.

Can I fix Bosch WTG86401UC 4.0 cu ft 300 Series Condensation Dryer error E:21 myself?

Yes — the top-ranked community fix ("Replace Electronic Control Board") is rated hard difficulty and takes about 60 minutes. Tools needed: T20 Torx screwdriver, Flat-head screwdriver, Multimeter.

How much does it cost to repair Bosch WTG86401UC 4.0 cu ft 300 Series Condensation Dryer error E:21?

DIY cost: $20-$30. Professional repair typically costs $250-$400. Many homeowners save money by trying the top-ranked community fix first.

What other error codes does the Bosch WTG86401UC 4.0 cu ft 300 Series Condensation Dryer have?

The Bosch WTG86401UC 4.0 cu ft 300 Series Condensation Dryer has 8 other known error codes, including: E:01 (Restricted Exhaust Vent), E:03 (Maximum Drying Time Exceeded), E:04 (Heater Relay Stuck Open), E:07 (Drum Motor Not Rotating), E:11 (Restricted Exhaust — Secondary Alert), and 3 more.

Which other Bosch models have the E:21 error?

Error code E:21 also appears on 3 other Bosch models: WTG865H4UC 4.0 cu ft 800 Series Condensation Dryer, WTW87NH1UC 4.0 cu ft 800 Series Heat Pump Dryer, WTW87NH2UC 4.0 cu ft 800 Series Smart Heat Pump. The fix may vary by model, so check each model's specific page for tailored repair steps.

What other error codes does the Bosch WTG86401UC 4.0 cu ft 300 Series Condensation Dryer have?

The Bosch WTG86401UC 4.0 cu ft 300 Series Condensation Dryer has 8 other known error codes:

E:01 — Restricted Exhaust Vent (2 fixes)
E:03 — Maximum Drying Time Exceeded (2 fixes)
E:04 — Heater Relay Stuck Open (2 fixes)
E:07 — Drum Motor Not Rotating (2 fixes)
E:11 — Restricted Exhaust — Secondary Alert (2 fixes)
E:12 — Restricted Exhaust — Tertiary Alert (2 fixes)
E:13 — Maximum Drying Time Exceeded — Repeated (2 fixes)
E:17 — Lint Screen Temperature Sensor Error (2 fixes)

Which other Bosch models have the E:21 error?

Error code E:21 also appears on 3 other Bosch models:

WTG865H4UC 4.0 cu ft 800 Series Condensation Dryer (dryer) · 2 fixes
WTW87NH1UC 4.0 cu ft 800 Series Heat Pump Dryer (dryer) · 2 fixes
WTW87NH2UC 4.0 cu ft 800 Series Smart Heat Pump (dryer) · 2 fixes

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