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Severity: High

LG Dryer Error d90 – Causes & Fix

LG's duct sensor found a severe exhaust restriction (about 90%). Clean the whole vent before more loads.

Safety first · Consult a professional

At this level hot, lint-laden air is barely leaving the house: stop drying loads until the duct is cleared, and don't leave the dryer running unattended. With a gas dryer, a restricted vent can also push combustion gases back into the room – a working carbon monoxide alarm is essential.

  • Unplug the appliance or switch off the breaker before opening any panel. Mains voltage can kill.
  • Hot surfaces and hot water can cause burns. Let the appliance cool down first.

At a glance

Severity: 4/5 – High4/5

Severity: High

Meaning
Exhaust Duct About 90% Blocked – Needs Attention Now
Typical repair cost
$15–$900
DIY difficulty
Easy

d90 is the middle of LG's three duct-restriction levels on vented dryers: LG states the dryer has detected roughly a 90 percent blockage in the ductwork and that it needs immediate attention. Where d80 is an early warning, d90 usually means the problem is no longer just a dirty lint screen – lint has packed into the wall duct, the run has sagged and filled, or several restrictions add up (long run, many elbows, a screened hood). Some LG models stop heating to protect themselves when the restriction gets this bad; others finish the cycle with very long drying times. Either way, LG's guidance is not to keep using a dryer with a severely restricted exhaust until the vent has been cleaned or repaired.

How it looks on the display

LG Dryer display showing error d90

Model families & display variants

Model familyShowsNote
LG vented dryers with Flow Sensed90About 90 percent restriction – clean the vent before further use.
Earlier warning on the same systemd80About 80 percent – dryer still runs, clean soon.
Highest leveld95About 95 percent – near-total blockage.
Alternate spellingsD90 / d 90Same code written differently in manuals and online.

Symptoms

  • d90 appears, often together with a full Flow Sense bar indicator
  • A normal load of towels needs well over an hour
  • Humid, warm air in the laundry room while the dryer runs
  • Only a faint puff of air at the outside vent
  • The code came back soon after the lint screen was cleaned
  • Lint visible at duct joints or around the dryer outlet

Possible causes

Ranked by how often each cause is behind this code (editorial estimate).

  1. Lint compacted inside the wall or attic duct section 34%
  2. Several smaller restrictions adding up: long run, extra elbows, a sagging flex section 22%
  3. Outside hood with a screen or guard that has filled with lint 14%
  4. Transition hose partly crushed behind the dryer 12%
  5. Roof or soffit termination that lint and debris can't escape from 10%
  6. Lint screen blinded by fabric-softener film 8%

Fix it step by step

Diagnostic flow: d901Stop and take the load out2Measure the run against the rules3Clean from both ends4Remove screens and fix the hood5Replace sagging or foil duct6Verify with a full load

  1. Stop and take the load out

    End the cycle, let the dryer cool and remove the laundry. Don't try to finish the load while the duct is this restricted.

  2. Measure the run against the rules

    Estimate the duct length from dryer to outside and count the elbows. Common US code allows about 35 feet of 4-inch smooth metal duct, minus 5 feet for each 90-degree bend, unless the dryer's installation guide permits more. A run beyond the limit will keep producing d90 even when clean.

    Tools: Flashlight

  3. Clean from both ends

    With the dryer unplugged and pulled out, detach the duct at the wall. Brush the run from the inside toward the outdoors and then from the outside hood back in, vacuuming lint out at each end so it isn't just pushed into a bend.

    Tools: Soft brush, Gloves, Screwdriver

  4. Remove screens and fix the hood

    A bird or rodent screen on a dryer hood catches lint and closes up quickly. Replace it with a hood that has a free-swinging damper and no screen, and make sure the damper swings fully open.

    Tools: Screwdriver

  5. Replace sagging or foil duct

    Sections of foil or vinyl accordion duct, especially in attics or crawl spaces, sag and fill with lint. Replace them with smooth rigid metal joined with foil tape, supported so it can't dip.

    Tools: Screwdriver, Gloves

  6. Verify with a full load

    Reconnect, check the transition hose isn't pinched, then dry a normal load. The Flow Sense bars should drop and d90 should not reappear; if it drops only to d80, some restriction remains.

How to reset d90

  1. Clear the duct restriction – a reset alone won't stop the code returning.
  2. Turn the dryer off with Power, then back on.
  3. Run a complete load; the sensor re-evaluates the duct during drying.
  4. If d90 returns right after a thorough cleaning, have the duct run inspected professionally.

Where the parts are

Dryer: lint filter and exhaust vent path – d901234567
Dryer: lint filter and exhaust vent path
  1. 1Lint filter
  2. 2Exhaust vent
  3. 3Heating element
  4. 4Condenser
  5. 5Motor
  6. 6Temperature sensor
  7. 7Door switch

Repair options & costs

RepairDIY?Estimated cost
DIY duct cleaning with a brush kit Yes $20–$50
Replace screened hood with a damper hood Yes $15–$45
Replace foil/vinyl sections with rigid metal duct Yes $30–$90
Professional dryer vent cleaning No $120–$250
Reroute duct or add a code-approved booster fan No $350–$900

Rough US estimates; technician call-out fees vary by region. Not a quote.

When to call a technician

Hire a dryer vent cleaning company when the duct runs through an attic, a roof or a long wall cavity you can't reach, or when d90 returns within a few weeks of cleaning. If the run is simply too long, a contractor can reroute it or install a booster fan that's approved for dryer exhaust.

Frequently asked questions

What's the difference between d80 and d90 on an LG dryer?

Both come from the same duct blockage sensor. d80 is the early warning, d90 means the restriction is severe and LG asks for immediate attention rather than cleaning when convenient.

I cleaned the duct and still get d90 – what now?

Measure the run length and count the elbows. A duct that's too long or too convoluted restricts airflow even when clean, and only rerouting or a booster fan fixes it.

Can I use a lint trap box indoors instead?

Not with an electric vented dryer that's showing d90, and never with a gas dryer. Indoor lint boxes vent moisture and fine lint into the house; the fix is a proper outdoor duct.

Will a screen on the outside vent keep pests out safely?

Screens on dryer vent hoods trap lint and are a leading reason for recurring restriction codes. Use a hood with a gravity damper or a pest guard designed for dryer vents that has no mesh.

Sources