LG Dryer Flow Sense Sensor: How to Clean, Test & Replace It

Flow Sense doesn't have a single 'sensor' you can point at — LG infers airflow from thermistor readings in the exhaust path. When owners ask about the Flow Sense sensor, they're usually in one of two places: the vent is verifiably clean but codes persist (a sensing fault), or they want to maintain the sensing path. This page covers both honestly: what the 'sensor' is, how to clean what can be cleaned, how the thermistors are tested, and when replacement is a technician's call.

What the 'sensor' actually is

LG's system uses temperature sensors (thermistors) in the dryer's exhaust/blower area and the control's model of how temperatures should behave with free airflow. There is no airflow paddle or pressure switch to clean. The practical 'sensor maintenance' is therefore: keep the lint path the thermistors live in clean (filter housing, internal duct), because a thermistor buried in lint reads the lint, not the air.

Cleaning the sensing path

Unplug the dryer. Remove the lint screen and vacuum the housing slot thoroughly (a crevice tool reaches the fines). On many models the exhaust thermistor sits at the blower/filter housing outlet — accessible with the front or rear panel off; a lint-packed sensor area is common on high-mileage machines and cleaning it restores honest readings.

Testing and replacing thermistors

LG does not publish owner test values for its dryer thermistors — there is no LG-documented resistance figure to meter against, and any exact ohm number quoted for these sensors is not coming from LG. LG's documented path for a temperature-sensor code is the factory reset; if the code persists after it, the unit needs service. A technician tests the sensor and its harness with the model's service documentation and replaces what is out of family. If the sensors check out but codes persist, the board's interpretation is the remaining suspect — technician diagnosis.

Rule out the vent first — really

Nine-plus times out of ten, Flow Sense codes with a 'bad sensor' suspicion end with a vent restriction the owner hadn't found (an elbow packed solid, a hood painted shut). Verify the vent by the disconnect test (brief supervised run with the hose off, electric models) before buying any sensor.

What Flow Sense actually is — and what it is not

Start with the correction this page owes you, because almost everything sold or searched under the phrase 'Flow Sense sensor' rests on a misunderstanding. LG's own manuals define Flow Sense as a sensing system, not a sensor: in LG's words, the dryer features Flow Sense, an innovative sensing system that automatically detects blockages and restrictions in dryer ductwork. There is no single airflow paddle, probe or pressure switch inside an LG dryer that you can unplug, clean and replace to service Flow Sense, and LG publishes no part number for such a component, because the function is performed by the dryer's existing temperature sensing and control logic judging how the exhaust behaves. When the result displeases it, the dryer reports a graded warning — d75, d80, d90 or d95 for a duct clogged about 75, 80, 90 or 95 percent — and, as LG's Canadian guidance stresses, those warnings are safety alerts about your venting, not malfunctions of the dryer. So 'clean, test and replace the Flow Sense sensor' resolves, honestly, into three real jobs: clean the vent path the system judges, test the duct condition using LG's own installation test, and replace the components LG actually documents when a warning survives a proven-clear vent — the duct itself, and in the rare machine-side case, the blower, which is a service diagnosis.

Cleaning, step one: the lint filter and its housing

Every Flow Sense investigation LG publishes begins at the lint filter, and the cleaning it means is more than peeling the felt off the screen. Remove the filter before every load, as LG instructs, and periodically wash it: LG's Flow Sense checklist says to wash the filter with soap if it is coated and to dry it fully before use, because fabric-softener and dryer-sheet residue forms an invisible film that air and water both struggle to pass. The home test is simple — run water over the clean-looking screen; if it pools instead of passing through, the film is there and the dryer has been breathing through it on every cycle. Vacuum the filter housing slot while the filter is out, since the fines that collect below the filter sit directly in the airstream the control is judging. Reinsert the filter firmly and fully: LG's dryer guidance treats a filter that is out of its housing as a fault state of its own, so a filter left slightly proud after cleaning can keep airflow complaints alive even with a spotless duct behind it.

Cleaning, step two: the hose, the duct run and the outside hood

The duct system is the component Flow Sense actually measures, so this is where 'cleaning the sensor' really happens. LG's checklist works the path in order: disconnect the exhaust hose and check it for kinks and crushing, vacuuming out its lint and keeping it short and straight; then clear the vent duct itself, brushing or vacuuming lint along the full vent path, and hire a vent cleaning service when the run is too long to reach properly; then check the outside vent hood, whose flap should open freely and be cleared of lint, debris and nests. Two of LG's details decide whether the clean counts. First, the replacement material: reconnect with rigid or semi-rigid metal duct, and avoid foil or plastic ducts, whose corrugations and collapse are themselves restriction sources. Second, completeness: a duct cleaned at both ends but not in its middle elbows is still the duct that earned the warning, because LG's error guidance warns that long runs and runs with multiple bends hide exactly the blockages that are hardest to trace. This is also the stage to keep the area around the dryer clear and confirm, on a test run, that air is genuinely leaving the house at the hood.

Testing the system: LG's installation test (duct check)

LG gives owners a genuine test for this system, and it is not a multimeter procedure — it is the installation test, also called the duct condition test, built into the dryer for exactly this purpose. LG's manuals describe running it once installation is complete to alert you to existing problems in your home's exhaust duct, and the same test is the correct verdict after any vent cleaning. The entry method is model-specific — manuals for different LG dryers name different button pairs to hold while pressing Power (Energy Saver plus Temp. on some models, Damp Dry Beep plus Temp. Control on others), after which the display shows its test indication and, on pressing Start/Pause, the dryer runs for approximately two minutes testing for blockages or restrictions to airflow in the ductwork. Read the result the way the manuals teach: no bars in the Flow Sense display means the ductwork is free of blockages or restrictions, while a full set of bars means a blockage that needs removing immediately — and do not interrupt the test cycle, because the manuals warn the results can be inaccurate if you do. Two of LG's caveats belong in your notebook: run the test with the dryer cool and the drum empty, since a warmed-up dryer or a loaded drum distorts it; and expect the installation test and normal operation to disagree occasionally, because LG states the test performed during normal operation gives more accurate information about the duct than the installation test does.

The sensors that do exist — and what LG says about servicing them

Two real, documentable sensors work alongside Flow Sense in an LG dryer, and keeping them straight prevents a great deal of wasted effort. The humidity (moisture) sensor is the one LG gives owners a maintenance task for: its error code is HS, and LG's instruction is to clean the sensors inside the dryer, located below the lint filter, with a damp rag or paper towel and let them dry fully before another cycle — softener residue on those strips is a drying-accuracy problem, and while LG does not blame HS hardware for Flow Sense warnings, the strips live in the same lint environment and deserve cleaning in the same session. The thermistors are the second group: they are the dryer's temperature sensors, monitored under the tE error family (tE1 and tE3 in LG's dryer list indicate a problem detected with the thermistor). Here LG's documentation deliberately stops at the owner's door — its remedy for a tE code is a factory reset, then repair service if the code persists, and it publishes no resistance values, test points or replacement procedure for owners. So the honest boundary is this: lint filter, yes; moisture strips, yes, with a damp cloth; duct system, yes, thoroughly; thermistors, no owner test exists in LG's material, and any source quoting you an exact ohm figure to test a Flow Sense or thermistor reading against is not quoting LG.

When the vent is proven clear: the blower branch, and replacing the right thing

Suppose the filter is washed, the duct is brushed end to end and rebuilt in metal, the hood moves freely, strong air leaves the house — and the Flow Sense warning still appears across several cycles. LG anticipates precisely this outcome and gives it a name: if, after having replaced the venting duct and cleaned it, the Flow Sense warning still appears, LG says it is possible the dryer blower fan is defective, and recommends contacting LG Customer Service. That single sentence defines the whole 'replacement' story for this system. There is no sensor to swap first; the documented suspects are the duct (replace crushed, foil or over-long sections with rigid or semi-rigid metal, routed shorter and straighter) and then, as a service matter, the blower that moves the air the system judges. Give the dryer its fair chance to agree with you before making that call: LG's manuals note that after a restriction is cleared, Flow Sense may need multiple consecutive cycles to determine that performance has improved before its indicator resets, and only an indicator still active after more than five cycles on a cleared vent earns the service request. Arrive at that call with your evidence ready — what was cleaned, what was replaced, the result of an installation test, and the airflow you felt at the hood — and the visit starts at the blower instead of repeating your vent work.

Keeping Flow Sense quiet: the maintenance rhythm LG recommends

Flow Sense never sleeps, so the goal is not to satisfy it once but to keep the duct in the condition it approves of. LG's published rhythm is simple: clean the lint filter before every load and wash it with soap whenever a film builds; deep-clean the vent system every six to twelve months; keep the transition hose short, straight and metal; and keep the outside hood free-moving and clear. Run the installation test after any duct work, after moving the dryer, and whenever drying times begin creeping up — the creep is the system grading your vent downward long before a d-code appears. Treat the earliest warning as the cheap one: a d75 or d80 is LG asking for a scheduled clean, while d90 and d95 are the same request at emergency volume, with LG's manual instruction not to use the dryer until the exhaust is cleaned or repaired. A dryer maintained on that rhythm rarely meets the top codes at all, and its Flow Sense indicator becomes what LG designed it to be — a quiet gauge you glance at, not an alarm you live with.

The Flow Sense blockage scale: d80, d90 and d95

Full guide: LG Dryer D80 Error Code — meaning, causes and fix.

Key takeaways

• A manometer isn't needed for the vent test — your hand at the exterior hood (strong warm flow) plus the disconnect test tells the story.
• Keep the sensor area lint-free at every filter wash; it's two minutes with a vacuum crevice tool.

Resetting the LG dryer

LG dryer codes clear with a power cycle: unplug for about 5 minutes, hold the Power button for a few seconds while unplugged on some models, restore power and run a test load. Flow Sense bars and codes like D80 are computed fresh from airflow measurements each cycle, so they only 'reset' by fixing the airflow — a power cycle alone cannot clear a genuine restriction.

Frequently asked questions

Related guides

Facts on this page were checked against manufacturer documentation: www.lg.com · www.lg.com · www.lg.com