Quick answer
Unplug the subwoofer (just the sub, leave the soundbar on), wait a full 30 seconds, and plug it back in. Most subs re-link on their own within a minute. If the blue LINK light keeps blinking, run the manual ID SET pairing below. Solid blue means you're connected.
What the lights are telling you
The LED on the back of the sub is the whole diagnostic readout, so read it before touching anything. A solid blue LINK light means the sub is paired and working; if you have no bass with a solid blue light, your problem is settings or content, not pairing. A blinking blue light means the sub is searching for the soundbar and can't find it. A red light means standby, which is normal when the soundbar is off.
This matters because people replace subs that were never broken. Blinking blue is a handshake problem, and handshake problems are fixable at home in about five minutes.
Try this first
- Unplug the subwoofer's power cord from the wall. Leave the soundbar plugged in and powered on.
- Wait at least 30 seconds. Shorter waits often don't clear the wireless module, and this is the step most people rush.
- Plug the sub back in and give it up to a minute. On most Samsung pairs the link re-establishes automatically and the LED goes solid blue.
- Still blinking? Move the sub within a few feet of the soundbar temporarily. If it pairs up close but drops at its normal spot, you have an interference or placement problem, not a broken sub.
The ID SET re-pair, step by step
This is Samsung's manual pairing procedure, and it fixes the large majority of stubborn cases.
- Leave both units plugged into the wall, then turn the soundbar OFF (standby). It must be off, not unplugged.
- Find the small recessed ID SET button on the back of the subwoofer. Press and hold it with a paperclip or SIM tool until the standby light turns off and the blue LINK LED starts blinking rapidly. That usually takes about five seconds of holding.
- With the blue light blinking, press and hold the Up button on the soundbar remote for about five seconds until ID SET appears on the soundbar's display. On older models without an Up-button pairing function, hold Mute instead.
- Turn the soundbar on while the sub's blue LED is still blinking. The display shows the link confirmation and the LED goes solid blue.
- Play something bass-heavy and confirm. If the display never showed ID SET, start over from step 1; the timing matters more than people expect.
If ID SET won't stick
A pairing that takes but keeps dropping points at the room, not the hardware. The wireless link between bar and sub runs in the same crowded spectrum as everything else in your house, so keep the sub within about 10 feet of the bar with clear line of sight, and get it out of enclosed cabinets. Routers are the usual offender; even three feet of separation between the sub and a Wi-Fi router makes a real difference.
Firmware is the other quiet culprit. Update the soundbar through the SmartThings app, or by USB from Samsung's support site if your bar isn't network-connected. Several Q-series link-drop complaints have been fixed by firmware updates alone.
When the subwoofer is actually dead
If the sub shows no LED at all on a wall outlet you've tested with another device, the internal power supply has likely failed. That's a repair or warranty case, not a settings case. Samsung covers these for one year in the US, so check your purchase date before paying anyone.
One thing worth knowing before you shop for a fix: Samsung wireless subwoofers are model-matched to their soundbars. A sub from a Q-series bar won't pair with a B-series bar, and buying a random used SWA sub on eBay rarely ends well. Out of warranty, the realistic path is a new bar-and-sub set rather than a standalone sub.
FAQ
Q: My sub is paired (solid blue) but I get no bass. What now? A: Raise the subwoofer level in the soundbar's sound settings (most remotes have a dedicated woofer button), and check you're not in a night or voice-enhance mode that ducks bass.
Q: Does unplugging the soundbar help too? A: Sometimes. If the sub-only power cycle fails, power-cycle both units for 30 seconds, then retry ID SET.