Why Is My Kohler Smart Toilet Not Flushing Automatically

Problem Description

Your Kohler smart toilet does not flush automatically when you leave the seat, or automatic flushing activates at random times without use. Automatic flushing in Kohler smart toilets uses an infrared proximity sensor to detect presence and departure — false triggers and missed flushes are both caused by sensor calibration, battery level, or obstructions in the sensor field.

Why This Happens in Real Homes

Automatic flushing on a Kohler smart toilet works off an infrared proximity sensor that detects when a user is present and then departs, so both missed flushes and random phantom flushes come back to that sensor's condition and settings. The first checks are the simplest: confirm auto flush is actually enabled in settings (it can be turned off, or suppressed by a power-save mode), and clean the sensor area, since a filmed or obstructed sensor can't reliably detect presence or departure. Raising the sensitivity helps when the sensor is present but under-detecting.

When the basics are fine, the sensor likely needs recalibration - resetting the toilet re-establishes its baseline so it stops both missing standing users and firing at random. On powered models, don't overlook the electrical side: a tripped GFCI or a brownout reduces the power the sensor and flush mechanism need, so a toilet that suddenly won't auto-flush may simply have lost full power. Obstructions in the sensor's field - a bathmat, a robe, anything hanging in the detection path - also cause false or missed triggers, so keep the sensor's line of sight clear. The manual and remote flush working while auto flush doesn't confirms the valve and water are fine and the issue is purely in the sensing.

Symptoms

• Auto flush doesn't activate when you stand
• Manual flush button works fine
• Remote-control flush works
• Sensor light not illuminating
• Auto flush worked before but stopped
• Seat sensor not detecting presence
• Auto flush fires at random with no use
• Flush is delayed after departure

Recognize these? Here's what usually causes it.

Common Causes

• Auto flush disabled in settings
• Seat/proximity sensor dirty or blocked
• Sensor sensitivity set too low
• Power-save mode active
• Seat not detecting the user (occupancy sensor)
• Sensor needs recalibration
• Low power / tripped GFCI on powered models
• Obstruction in the infrared sensor field

Tools & Requirements

Step-by-Step Solution

1

Check and Replace Batteries

Kohler smart toilets and seat units run on 4 AA batteries. When battery voltage drops below threshold, the proximity sensor misfires — either failing to trigger on departure or activating randomly. Replace all batteries with fresh name-brand alkaline AA. After replacement, wait 30 seconds for the sensor to recalibrate, then sit on the seat for 30 seconds, stand, and wait 10 seconds for the auto-flush to trigger.

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2

Clean the Proximity Sensor Window

The auto-flush sensor is a small dark lens window on the back of the toilet seat unit, facing toward where the user sits. Mineral scale, cleaning product residue, and splash deposits accumulate on this window and cause erratic sensor behavior. Clean the sensor window with a soft damp cloth. Do not spray toilet bowl cleaner directly at the sensor area — chemical residue affects IR transparency. After cleaning, test with a full sit-and-depart cycle.

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3

Adjust Sensor Sensitivity and Detection Range

In the Kohler Konnect app, go to the toilet settings and look for Auto Flush Sensitivity or Detection Range. If the toilet flushes randomly (too sensitive), reduce sensitivity. If it misses flushes when you stand (too low), increase it. The default factory setting is optimized for average use but may need adjustment for smaller users, children, or high-traffic bathrooms where residual heat from multiple users causes false triggers.

4

Remove Obstruction from Sensor Field

Objects placed on the toilet tank lid, decorative items near the rear of the toilet, or items hanging behind the toilet can enter the sensor field and trigger false flushes. Clear the area behind and above the toilet seat. Also check that the toilet lid is fully open when seated — a partially closed lid blocks the sensor from detecting presence correctly in some Kohler configurations.

5

Disable Auto-Flush and Use Manual Flush during testing

In the Kohler Konnect app, temporarily disable automatic flushing and use the manual flush button in the app or on the remote. This confirms the flush valve and plumbing are working correctly independently of the sensor. If manual flush works but auto-flush does not, the issue is definitely the sensor or its configuration. If manual flush also fails, the flush valve or water supply pressure needs inspection by a plumber.

Quick Solutions

Still having issues? This is usually the deeper cause below.

Need More Help? Kohler Support

Note: The contact information below connects you directly to Kohler's official customer support team, not Trunetto. They can help with warranty claims, device replacements, and advanced technical issues.