Keep the dryer off while you check
- D90 warns of severe exhaust restriction on LG dryers with duct blockage sensing. LG labels it 90% blockage.
- Stop using your dryer until the exhaust system has been cleaned and repaired. Start with the lint filter and connections you can see without moving the dryer.
- If the restriction isn't visible or the warning persists after corrections, get a professional vent assessment.
If your clothes are still damp, a blocked filter or exhaust duct can be behind it. We'd keep the dryer off while checking, because restricted airflow can cause excessive heat buildup and a fire. LG's US D90/D95 guidance dated January 20, 2024 (opens in a new tab) requires stopping use until the exhaust is cleaned and repaired.
The warning points to restricted airflow somewhere between your dryer and the outside exhaust exit. LG's general dryer troubleshooting covers electric and gas dryers with this exhaust setup.
As a labelled model example, the DLE3400W has a FlowSense duct clogging indicator, confirmed in LG's US specification sheet dated December 10, 2019 (opens in a new tab). The checks below use LG's broader dryer guidance.
Give the filter and clothes room for airflow
Remove lint from the filter between every load. For a wash, use warm water and a soft brush, then let the filter dry fully before reinstalling it, following LG's US filter guidance dated September 10, 2026 (opens in a new tab).
Reduce the load size so air can pass through the clothes from back to front. Keep the dryer off after these checks until the exhaust system has been cleaned and repaired.
Look for damage in the visible connection
With the dryer still off, look only at the exhaust connection you can already see. Leave moving the machine, disconnecting ducting and repairs to a professional. A crushed or damaged duct can block airflow.
- Look for visible lint buildup at the rear exhaust duct.
- Check the hose between the dryer and wall for crushing, dents, kinks, compression or other damage.
- Look for loops coiled over one another like a spring.
- Check for holes and loose connections.
Material wording differs between LG's guides. Its US error list (opens in a new tab) includes rigid, semi-rigid and flexible ducts in the crushing and kinking check, while its US D90/D95 guide (opens in a new tab) tells you to verify rigid or semi-rigid ducting. The flexible-duct mention isn't material approval for your dryer; have the vent specialist assess it.
If you see plastic or foil accordion ducting, ask the professional to address it. CPSC's general dryer fire-prevention guidance (opens in a new tab) calls for replacing it with rigid or corrugated semi-rigid metal duct because plastic and foil types trap lint more easily and are more vulnerable to kinks and crushing.
When cleaning hasn't settled it
A clean-looking connection still leaves hidden sections of the exhaust path to assess. Long duct runs and too many bends can create restrictions, so contact a local dryer-vent cleaning specialist if you can't see the problem or D90 returns after cleaning.
Ask the specialist to check lint accumulation, the full length from dryer to outside exhaust, the number of 90-degree bends and any needed modifications. Those are the assessment points in LG's US professional vent guidance (opens in a new tab). Keep the dryer out of use until the exhaust has been cleaned and repaired.
If the problem continues after troubleshooting and exhaust corrections, arrange appliance service for diagnosis. Use the Request a Repair option in that LG guide to schedule service.
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