The LG dryer D90 code means the dryer has detected that its exhaust duct is about 90% blocked. When the vent looks clear, the restriction is usually hidden: lint deep in the wall duct, a hose crushed behind the dryer, a stuck outside flap, or a duct run that is too long. Check the full vent path from the dryer to the outside, then run an empty test cycle. If the code stays after the duct is cleaned or replaced, LG says the blower fan may be faulty and needs service.
Quick facts
| Code | D90 (shown as d90; related codes are d80 and d95) |
|---|---|
| Appliance | LG electric and gas dryers with Flow Sense |
| What it means | Exhaust airflow is restricted by about 90% |
| Time needed | 30 minutes to 2 hours |
| Difficulty | Moderate |
| Most likely cause | Lint packed in the wall duct or a crushed hose you cannot see from the front |
The LG dryer D90 code on LG dryers (made by LG Electronics) is a serious venting warning, one step below d95. It is frustrating when the lint filter is spotless, but the problem is almost always further down the vent. For other codes, browse our dryer error code guides.
What does the LG dryer D90 code mean?
D90 means the dryer’s duct blockage sensor has detected a 90% blockage in the ductwork. LG’s d90 and d95 guide calls this a badly restricted exhaust that needs prompt attention, and warns not to use the dryer until the exhaust system has been cleaned and repaired.
The code comes from LG’s Flow Sense system. LG Canada explains that sensors watch for a sudden rise in temperature, then software estimates how quickly the exhaust is blocking. That is why D90 can appear even when you see no lint: the dryer is measuring heat buildup, not looking at the duct.
If you saw the LG dryer D80 code before, D90 means the same restriction has grown worse.
What causes the LG dryer D90 code with no visible blockage?
A “no blockage” D90 almost always means the clog or crush is somewhere you have not looked yet. LG lists lint deep in the duct, a damaged or kinked hose, a stuck vent flap, and long ducts with many bends as the main causes.
| Cause | How to check | Fix | DIY difficulty |
|---|---|---|---|
| Hose crushed or kinked behind the dryer | Pull the dryer out and look at the full hose, including where it meets the wall | Straighten it or replace it with rigid or semi-rigid metal duct | Easy |
| Lint deep in the wall, attic or roof duct | Run Air Dry and feel for weak airflow outside | Brush the whole run or hire a vent cleaning service | Moderate to pro |
| Outside flap stuck, screened or iced | Watch the flap with the dryer running; it should open fully | Clear lint, nests, snow or ice; replace a flap that cannot open | Easy |
| Duct too long or too many elbows | Measure the run and count 90-degree elbows | Shorten or reroute to LG’s limits | Pro (often) |
| Foil or plastic duct sagging and trapping lint | Look for soft, ribbed, saggy duct in walls or crawl spaces | Replace with 4-inch metal duct | Moderate |
| Wall cap closed or blocked (new homes) | Check that the cap opens and is not painted or taped shut | Free or replace the wall cap | Easy |
| Faulty blower fan | Code stays after the duct is cleaned or replaced | Contact LG service | Pro only |
| Sensor or control fault | Code appears with strong airflow outside on every load | Have a technician test the sensors | Pro only |
How do you fix the LG dryer D90 code? (step by step)
Start with the parts you can see, then work outward. Test after each step so you know which fix worked.
Total time: 1 hour
Turn off and unplug the dryer
Press Power, then unplug the dryer or switch off its breaker. On a gas dryer, also close the gas shutoff valve before moving it.
Clean the lint filter and its slot
Clear the lint filter, and wash it with soapy water if it looks waxy. LG also suggests cleaning inside the dryer, including the filter area, so vacuum out lint you can reach in the filter slot.
Inspect the hose behind the dryer
Pull the dryer out and disconnect the hose. LG says it must not be crushed, dented, kinked or compressed, must have no holes or loose joints, and should be straight or in an S-curve.
Clean or replace the hose
Brush or vacuum out the hose. If it is foil or plastic, replace it with 4-inch rigid or semi-rigid metal duct, as LG recommends.
Clean the full duct run
Brush the duct from the inside and from the outside opening. LG recommends a professional vent cleaner when the blockage is inside the walls or the run is long.
Check the outside flap with the dryer running
Reconnect the duct, start the Air Dry cycle and go outside. LG says the flappers must open fully with strong airflow; replace the cover if they cannot open.
Compare your duct to LG’s limits
LG’s limit for 4-inch rigid metal duct with a 4-inch wall cap is 65 feet with no elbows and 28 feet with four elbows. LG says to use no more than four 90-degree elbows, and a run past these limits can keep triggering D90.
Reset the dryer and run a test cycle
Unplug the dryer for about 5 minutes, plug it back in and run a timed dry with an empty drum. If D90 returns with a clean, short duct and strong outside airflow, book LG service.
On some models, the Flow Sense icon lights bars instead of a number. LG says two or four lit bars mean the exhaust is severely restricted, the same message as a d90 or d95 code.
Is it different on gas vs electric LG dryers?
The meaning and the vent checks are the same on both. Gas dryers need a little more care when you move them.
Electric dryers
- D90 is a venting problem first. Check the vent before you suspect a part.
- If the dryer also gives no heat, look for nP or PS codes, which LG ties to the home’s power supply.
Gas dryers
- Close the gas shutoff valve before pulling the dryer out, and avoid kinking the flexible gas line.
- Gas dryers vent combustion gases through the same duct. Never run a gas dryer with the duct disconnected or vented indoors.
- LG uses a separate gAS code (9A5 on some displays) when the dryer is not getting gas.
How do you reset an LG dryer after the D90 code?
D90 clears on its own once the dryer sees normal airflow. You only need to fix the vent and run another cycle.
- Fix and reconnect the duct.
- Unplug the dryer or switch off its breaker for about 5 minutes.
- Plug it back in, press Power and start a timed dry.
LG’s general control reset is to unplug the dryer, hold Start/Pause for 5 seconds with no power, then restore power. A reset will not hide a real blockage, because Flow Sense checks again during every cycle.
⚠️ Safety first
- Unplug the dryer or switch off its breaker before you move it or disconnect the vent.
- Disconnect power at the breaker before removing panels.
- On a gas dryer, close the gas shutoff valve first and never run it with the vent disconnected.
- If you smell gas, leave the home and call your gas utility or 911 from outside. Do not operate switches.
- LG warns that using a dryer with a severely restricted exhaust may be unsafe. Stop drying loads until the vent is fixed.
When should you call a technician?
Call when you have cleaned and checked the full vent and D90 still returns. LG says that if the warning persists after the duct is cleaned or replaced, the blower fan may be defective, and that ongoing problems need service. Clear signs include:
- Strong airflow outside, a short metal duct, and D90 on every load.
- You cannot reach part of the duct inside a wall, attic or roof.
- Your duct is longer than LG’s limits or has more than four 90-degree elbows.
- The dryer shuts off early, smells hot or the cabinet feels very hot.
- A gas dryer gives no heat with the valve fully open.
Use a vent cleaning service for the duct, and LG service or an appliance technician for the blower fan, sensors or controls.
How can you prevent the D90 code from coming back?
Keep the full vent clean and short. The US Fire Administration found that failure to clean was the leading factor in residential dryer fires, so these steps also lower fire risk.
- Clean the lint filter every load.
- Deep-clean the whole vent system every 6 to 12 months, as LG Canada recommends.
- Use 4-inch rigid or semi-rigid metal duct with as few elbows as possible.
- Check the outside flap a few times a year, and after snow or storms.
- Leave space behind the dryer so the hose is never crushed against the wall.
Frequently asked questions
Why does my LG dryer say D90 when there is no blockage?
The dryer reads heat buildup, so a hidden restriction still triggers it. The most common hidden causes are a crushed hose behind the dryer, lint deep in the wall duct, a stuck outside flap or a duct that is too long. If all of these check out, LG says the blower fan may be faulty.
Can I keep using my LG dryer with a D90 code?
LG says not to use the dryer until the exhaust system has been cleaned and repaired. A 90% restriction makes the dryer run hot and slow. Fix the vent first.
How do I clear the D90 code on an LG dryer?
Fix the vent, then run another cycle; the code clears once airflow is normal. If it lingers, unplug the dryer for about 5 minutes and try again.
Is D90 worse than D80 on an LG dryer?
Yes. D80 means about an 80% restriction and D90 about 90%. D95 is the most severe level.
Can a long dryer vent cause the D90 code?
Yes. LG says long ductwork or too many bends can cause blockages, and it limits 4-inch rigid metal duct to 65 feet with no elbows, less for each elbow. A run past those limits can trigger D90 even when it is clean.
Can a bad part cause D90 on an LG dryer?
It can, but only after the vent is ruled out. LG names a defective blower fan as a possible cause when the warning continues after the duct is cleaned or replaced.
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