Lg dryer flow sense flashing

Flow Sense indicator showing four bars or lit during the cycle. The dryer has detected a restriction in the outside exhaust duct. The dryer still runs, but drying takes longer and uses more energy.

Cause 1 of 4The exhaust system is too long or has too many turns or restrictions. Source: Troubleshooting: Operation, p. 51

First checkInstall a shorter or straighter duct run, as described in the installation instructions.

Causes and checks

The exhaust system is too long or has too many turns or restrictions. Source: Troubleshooting: Operation, p. 51
1. Install a shorter or straighter duct run, as described in the installation instructions.
Lint or a foreign object partly blocks the ductwork. Source: Troubleshooting: Operation, p. 51
Qualified technician Have the ductwork checked and cleaned right away. The dryer can be used in this condition, with longer drying times and higher energy use.
The indicator stays on for 2 hours after the end of a cycle when a restriction was sensed. Source: Troubleshooting: Operation, p. 51
1. Open the door or press the Power button to turn the display off.
The indicator is still on after the restriction was cleared. Source: Troubleshooting: Operation, p. 51
1. Run several consecutive cycles. Flow Sense needs them to confirm that performance has improved before it resets.
LG Customer Information Center If the indicator is still on after more than five cycles, contact LG service. Contact: 1-800-243-0000 or lg.com/us/support.

Service

If the checks above do not clear it, contact LG Customer Information Center: 1-800-243-0000, lg.com/us/support. United States (Canada: 1-888-542-2623). Source: Limited Warranty: To Obtain Warranty Service, pp. 58, 64

Other DLEX3900W indicators

d80, d90, d95: The exhaust system is restricted: too long, too many turns, or blocked. LG says not to use the dryer until the exhaust system is cleaned or repaired.
tE1 to tE7: Temperature sensor failure.
Ps: The power cord is connected incorrectly.
bIG: Not a fault. The steam option is set for a big item such as a comforter, because the More Time button was pressed.
CL: Not a fault. Control Lock is on, so every button except Power is locked. The door is not locked.

Sources

Owner's Manual, Dryer DL*X390**. LG Electronics Inc. Document MFL70442672, revision Rev.00, 2024-02-26, 64 pages, en-US. gscs-b2c.lge.com. Listed on the manufacturer's support page. Retrieved 12 November 2026.
Owner's Manual, Dryer DL*X400** / DL*X408**. LG Electronics Inc. Document MFL70442676, revision Rev.02, 2026-06-25, 60 pages, en-US. gscs-b2c.lge.com. Listed on the manufacturer's support page. Retrieved 12 November 2026.

Page numbers are the numbers printed in the manual. Where this page and the manual differ, follow the manual.

Applies to: DLEX3900W (variants DLEX3900B; DLGX3901W; DLGX3901B), DLEX4000W (variants DLEX4000B; DLGX4001W). United States and Canada.
Source: Owner's Manual, Dryer DL*X390**, MFL70442672 revision Rev.00, 2024-02-26; Owner's Manual, Dryer DL*X400** / DL*X408**, MFL70442676 revision Rev.02, 2026-06-25
Last verified: 12 November 2026
Handbook: LG DLEX3900W and DLEX4000W steam dryers in Dryers; all LG handbooks