The short answer
On Bosch WTG dryers a load that tumbles without ever getting warm is far more often a protection device that has already done its job than a failed heater. Heat is the part of the cycle that depends on airflow, so anything that restricts air on the seven models below shows up as no heat rather than as poor airflow. Work the air path and the supply first, and the expensive parts last.
What you observe on these models
- A full cycle ends with the load barely drier than it went in — The owner-side definition of this fault, and the one that brings most calls in.
- No warmth at the door when you open it mid-cycle — Open the door partway through and feel the air, not the drum wall.
- The machine skips to the end far too early — A sensing machine that reads the load as dry will end a cold cycle quickly rather than run long.
- A faint hot smell on the last cycle that worked — Worth remembering, because it points at lint and heat rather than at an electrical part.
- NEAR MISS - heat is fine but the load is soaked in one spot — That is a loading or a drum-seal question, not a heating fault.
Causes, most likely first on the WTG family
- A supply problem that leaves the drum turning — First on the WTG family, because it is free to check and it mimics every expensive fault. A machine can have enough supply to run its motor and control and still be missing what the heater needs, and the panel will report nothing. Check this before you buy a part.
- Thermal protection opened by a restriction — Second. The chain of thermostats and cut-outs is the machine protecting itself, and on the seven models below it opens quietly: nothing on the panel says it has happened.
- The air path that opened it — Third in rank but always second in the work, because fixing the protection without fixing the restriction guarantees a second failure. Filter, secondary filter or condenser, and the duct if you have one.
- Heater, sensor or control board — Last. Ranked here because everything above it is either free or cheap to eliminate, and because a dead heat source is unmistakable once the three above are clean: no heat, every cycle, without exception.
Check in this order, and why
- First: confirm the breaker and the outlet — Placed first because it costs nothing, takes a minute, and rules out the one failure that perfectly imitates a dead heater on the seven models below.
- Second: run a short timed cycle and feel the air — Feel the air leaving the machine, not the drum. Warm air with a wet load is an airflow problem; cold air is a heat problem.
- Third: clear the whole air path — Filter, secondary filter or condenser if fitted, then the duct. Do all of them before running again, so a second test means something.
Before you open anything
Safety
Unplug the dryer or switch off its breaker before removing any panel; a capacitor can hold a charge after the power is off. Treat the exhaust path as a fire risk rather than a performance question - lint packed around a heat source is what turns a no-heat call into a fire. If the machine has ever tripped its breaker or smelled hot, stop here and have it looked at rather than running it again to see what happens.
Models in the WTG family
Reference| Model number | Family key |
|---|---|
| WTG86400UC | bosch:dryer:wtg |
| WTG86401UC | bosch:dryer:wtg |
| WTG86402UC | bosch:dryer:wtg |
| WTG86403UC | bosch:dryer:wtg |
| WTG865H2UC | bosch:dryer:wtg |
| WTG865H3UC | bosch:dryer:wtg |
| WTG865H4UC | bosch:dryer:wtg |
When to call a technician
The line on the seven models below is the first fixed panel. Filters, ducting and the breaker are yours; everything from the thermal chain inwards is a service call, because a cut-out replaced without finding what opened it fails again and the second failure is more expensive than the first. Any smell of burning moves this from a repair to a safety call.
Other faults covered for the WTG family
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
