E298 No Power

[Jongirl24]

Hello! My Nest has been working fine for months! Today, I’m getting a No Power error code - e298. 

The wires that are connected are yellow, white, green, and red. When I check the wiring info on the thermostat it says all are undetected. 

I’ve tried to reinsert all the wires and restart but no luck. Please help! Not sure how it was working yesterday but today there is an issue with wires?!

[Markjosephp]

Hi Jongirl24,

Thank you for taking the time to let us know about your inquiry. I'd be happy to take a look at this for you.

Your system may not provide enough power or any power to either the thermostat or a specific wire (so the thermostat can’t complete a circuit and shows the message No power to the R terminal). To isolate:

• Have you checked that the breakers are on?
• Were there any recent HVAC system maintenance projects?
• Are you experiencing extreme weather lately?
• Do you still have your old thermostat? If so, you can try installing it to see if it detects the wires.
• Checked the air filter.
  • A clog in the air filter can limit how much air flows over the cooling coils. If the clog persists, the cooling coils can freeze and cause the system to shut off.
• Inspect your system's drip pan or drain tubes.
  • The drip pan may be full of water, or the drain tube may have a clog, and the AC may shut itself off to prevent an overflow of water.
• Check if your utility company has installed an energy savings box.
  • Some energy companies install boxes that cut off the power during high-demand times.
• Check the condition of the HVAC fuse.
  • Sometimes, fuses burn out due to one or more reasons. If the HVAC fuse burns out, the system may cut off the power to the thermostat and show no power.

Please check out this article to troubleshoot a "no power" alert on the Nest Thermostat (E298 or M20 help code) and let me know how it goes.

Regards,
Mark