What Does the D90 Code Mean on an LG Dryer?

1. Read the warning before another load

A damp load makes another cycle tempting. We'd keep the dryer off and check the filter first, because lint that blocks airflow can cause excessive heat and a fire. D90 points to the exhaust path from the dryer to the outlet outside your home.

What D90 tells you about the exhaust

On LG dryers with duct blockage sensing, D90 means the dryer has detected a potentially blocked exhaust that needs immediate attention. The 90% figure is LG's blockage designation for this warning. Check the exhaust path to find which section needs work.

These exhaust checks apply to LG electric and gas dryers with this warning. The restriction can be anywhere between the appliance and the outside exhaust exit, including the home's ductwork and the connection behind the dryer.

The LG DLE3400W, for instance, has a FlowSense duct clogging indicator. You don't need to match that particular model to begin the filter and visible-connection checks.

2. Clean and dry the lint filter

Remove accumulated lint so the filter is clear of blockages. Clean it before or after every drying cycle. If you wash it, use warm water and a soft brush, then let it dry fully before putting it back.

A lint-covered filter gives you one restriction to clear. Whether you found lint or the filter was already clean, continue to the visible exhaust connection. Clothes that stayed damp after a typical cycle or took longer than normal to dry are useful details to mention when booking the vent assessment.

3. Set aside part of a crowded load

Reduce the load size so air has room to pass through the clothes from the back of the drum toward the front. Set some clothes aside if the drum is crowded.

A smaller load addresses airflow through the clothes. Continue checking the exhaust even if the load was already small, since D90 points to a restriction along that route.

4. Look at the connection behind the dryer

With the dryer off, look at the exposed exhaust connection between the appliance and the wall. Keep this to what you can see without moving the dryer or disconnecting ducting.

• Look for visible lint buildup at the rear exhaust duct.
• Check for crushed, dented, kinked or compressed sections and other damage.
• Notice whether the hose is coiled over itself like a spring.
• Look for holes in the hose and loose connections.

Lint at the rear exhaust can cause long drying times, and a crushed or damaged duct can block airflow. Note exactly what you can see, such as a flattened section or a loose connection. If the connection looks intact, check its material and the outside outlet next.

The exhaust hose should be straight or follow an S curve, rather than loop over itself like a spring. Include a different shape in your description of the connection.

5. Check what the connection is made of

For an LG dryer displaying D90, the exhaust connection should be rigid or semi-rigid ducting. Check the visible material as well as its shape.

If you see plastic or foil accordion-type ducting, ask the vent specialist to replace it with rigid or corrugated semi-rigid metal duct. Plastic and foil types can trap lint more easily and are more prone to kinking or crushing, which can greatly reduce airflow.

The CPSC's dryer fire-safety advice (opens in a new tab) explains that material change. If the connection is already metal and intact, move on to the outside outlet.

If the connection or route needs replacing, our advice on planning a dryer vent installation can help you prepare for the discussion about materials and routing.

6. Look at the outside outlet

Find the exhaust outlet outside your home. Look for a damaged hood, visible lint clogging or an obstructed area around it. A clear-looking outlet sends you to the hidden sections of the duct next.

The outlet may have flappers, a cage or mesh to keep animals or debris out. Lint can jam the flappers, which need to open fully. Note any visible problem and ask the vent specialist to check their movement and whether the cover needs replacing.

Our explanation of cleaning dryer exhaust shows how the outdoor opening fits into the full route.

7. Have the hidden duct assessed

If the visible connection and outlet look clear, the rest of the house duct still needs attention. Long runs and routes with multiple elbows, bends or transition ducts can create restrictions that are hard to trace.

If you've already had the vent cleaned, ask whether that visit also covered the route's length and bends. Cleaning lint out and checking the route answer different questions. If D90 appeared after installation, tell the specialist when it started so the routing is included in the assessment.

What to request at the vent visit

Contact a local professional dryer-vent cleaning company for inspection and repair of a hidden or unresolved restriction. Ask for an assessment from the dryer to the outside outlet, including the sections you can't see.

• Where has lint accumulated in the exhaust system?
• What is the total ventilation length from the dryer to the outside outlet?
• How many 90-degree elbows are in the route?
• What modifications does the ventilation system need?

Mention longer drying times, damp loads, visible duct damage or problems at the outside cover before the visit. If the warning continues after the exhaust has been cleaned and repaired, arrange appliance service for a diagnosis through LG's repair request (opens in a new tab).

A few questions before you book

8. Confirm airflow after the repair

Once the exhaust has been cleaned and repaired, check whether your model is listed in LG's dryer test instructions (opens in a new tab). If it is, empty the drum, remove any drying rack or other items, and close the door. Then use the button combination shown for your model, press Start/Pause to run the test, and check the Flow Sense result when the test ends. If your model isn't listed, use its installation-test instructions or contact LG for the correct procedure before drying again.

If the Flow Sense LED turns on or the restriction warning continues, arrange appliance service for a diagnosis. An unlit Flow Sense LED at the end of the test means the exhaust system is adequate. Once your model's installation test confirms adequate airflow and the dry filter is back in place, you can return to the waiting load.