Tumble Dryer
F18
The F18 error code on a Bosch tumble dryer indicates a draining fault — the machine cannot pump out condensed water properly. It’s a common issue, often fixable at home in under 30 minutes, but ignoring it will stop your dryer from completing any cycle.
What does this error mean?
Bosch condenser and heat pump tumble dryers collect moisture from your laundry in a water container or drain it away via a hose. The F18 code tells you the dryer’s pump is unable to empty this water within the expected time. The machine detects the water level isn’t dropping as it should and shuts down to protect internal components from overflow or damage.
Est. repair cost
£80–£150 professional pump replacement; £20–£45 DIY pump part if self-replacing
🔍 Likely causes
🛠️ Step-by-step fix
Reset the machine first: power off at the wall, wait 60 seconds, then switch it back on and restart a cycle. Occasionally a temporary sensor glitch triggers F18 and a reset clears it.
Empty and reseat the water container: pull it out fully, empty it completely, and push it firmly back in until it clicks. A poorly seated container is a surprisingly frequent culprit.
Check and clear the drain hose: if your dryer is plumbed into a waste pipe, pull the machine forward and inspect the hose for kinks, blockages, or a sag that’s trapping water. Straighten or flush it through.
Clean the condenser unit: locate the condenser panel (usually behind a flap at the bottom front of the machine), remove it, and rinse it thoroughly under a tap until the water runs clear. Refit it securely.
Clear the drain pump filter: place a towel and shallow tray under the pump filter cover (also at the bottom front). Slowly unscrew the filter cap, let the residual water drain out, remove any debris from the filter and pump cavity, then refit and tighten firmly.
Run a short test cycle: if the error has cleared after these steps, run a 30-minute cycle and monitor. If F18 returns immediately, the pump itself has likely failed and needs professional attention.
📞 When to call a professional
If you’ve completed all the steps above and F18 persists, the drain pump motor has most likely failed and needs to be replaced — this involves accessing internal electrical components and is not a DIY job. Call an appliance repair engineer and tell them: ‘My Bosch tumble dryer is showing F18, the filter and condenser are clear, and I suspect a faulty drain pump.’ This helps them bring the right part and saves you a call-out fee for a follow-up visit.
⚖️ Repair or replace?
A professional drain pump replacement on a Bosch tumble dryer typically costs £80–£150 including labour in the UK. If your dryer is under 5 years old, repair is almost always worth it — Bosch machines are built to last 10–15 years. If it’s over 8 years old and showing other signs of wear, weigh the repair cost against a new mid-range condenser dryer at £350–£500; in that case, replacement may make more financial sense.