The Nest Thermostat W5 error indicates your device's internal Wi-Fi radio has completely failed and cannot scan for any wireless networks. This is typically a permanent hardware failure of the Murata Wi-Fi chip, especially common on 3rd generation Nest Learning Thermostats, though low battery power can sometimes trigger the same error temporarily.
Quick answer
- Check battery voltage first — if below 3.6V, charge via USB for an hour as low power disables the Wi-Fi radio
- Perform a soft reset by holding the ring for 10 seconds until the screen goes black
- Reset network settings through Settings → Reset → Network Settings
- If W5 persists after these steps, the Wi-Fi chip has permanently failed and the unit needs replacement under warranty
Symptoms
- Thermostat displays Error W5 on the network settings screen
- Device shows as offline in the Nest app
- Thermostat cannot detect any Wi-Fi networks (the network list is completely empty)
- Battery voltage may read below 3.7V in Technical Info
Quick checks
Check your battery voltage immediately — press the ring and go to Settings → Technical Info → Power. Look at the battery reading:
- Below 3.6V: The radio was disabled to conserve power, not broken
- Above 3.7V: Power is sufficient, indicating a likely hardware failure
Try a different location — move within 10 feet of your router to rule out range issues, though W5 typically means the radio cannot scan at all regardless of signal strength.
Step-by-step fix
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Check battery power — press the ring and navigate to Settings → Technical Info → Power
- If battery voltage is below 3.6V, connect a USB cable and charge for one hour
- Retest after charging; the W5 error may disappear once power is restored
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Perform a soft reset — hold the thermostat ring down for 10 seconds until the screen goes black and you see a small green light flash
- Wait 2 minutes for the full reboot cycle to complete
- The device will restart and run through its initialization sequence
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Test network scanning — go to Settings → Network after the reboot
- If it successfully scans and shows available networks, reconnect to your Wi-Fi immediately
- If W5 appears instantly, this confirms hardware failure
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Reset network settings — navigate to Settings → Reset → Network Settings
- Select Network Settings only (not "All Settings" yet)
- Confirm the reset and wait for reboot
- Attempt to connect again through Settings → Network
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Update firmware if connection succeeds — if you manage to connect after any of these steps, immediately check for and install any pending firmware updates to prevent regression
If it still isn't working
Contact Google Support directly and specifically mention "Error W5" — they have specialized warranty procedures for this known hardware defect. Google extended warranties for W5 errors on certain serial number ranges, so check your coverage even if you think your warranty expired.
Continue using offline — your thermostat still functions perfectly as a manual temperature control. You can adjust heating and cooling normally using the ring; you just lose app connectivity and remote control features.
Do not attempt hardware repairs — avoid internet suggestions about freezing or heating the unit to "reflow solder." The device contains a lithium-ion battery that can be dangerous if damaged.
If Google confirms a hardware failure
The W5 error is one of the few Nest issues that's genuinely irreparable — if the Wi-Fi chip is gone, the thermostat is gone. If your unit is out of warranty and Google won't replace it, this is a natural point to look at what's current. The Nest Learning Thermostat (4th Gen) is the direct replacement and addresses the Wi-Fi chip reliability issues from the 3rd Gen. Alternatively, if you've been frustrated by the Nest ecosystem, this is a reasonable time to compare the Ecobee Smart Thermostat Premium — better heat pump support, included room sensors, and Apple HomeKit compatibility.
→ Best smart thermostats — Nest, Ecobee, and Honeywell compared
FAQ
Q: Can I fix the Wi-Fi chip myself? A: No. The Murata Wi-Fi chip is surface-mounted inside the device and cannot be repaired without specialized equipment. If soft resets and charging don't work, replacement is the only solution.
Q: Will a router reset help with W5 errors? A: No. W5 means the thermostat's radio cannot scan for any networks at all — it's not a connection or authentication problem. Router changes won't affect a device that cannot detect radio waves.
Q: Why is this more common on 3rd generation models? A: The 3rd generation Nest Learning Thermostat used a specific Murata Wi-Fi chip that has a higher failure rate over time. Google acknowledged this as a known issue and extended warranty coverage for affected units.
Q: How long does the warranty replacement process take? A: Google typically ships replacement units within 3-5 business days once they verify the W5 error. They may send the replacement before you return the defective unit.