topic Error M20/E298 in Nest Thermostats

Error M20/E298

Chergirl9 — Sun, 29 May 2022 01:25:03 GMT

Thermostat keeps saying "no power" and giving error codes M20 & E298 no matter what I do.

I correctly installed the c-wire power connector. There are no shorted fuses on my control board. My furnace is powering just fine.

When I look at the equipment errors, it says it cannot detect the W, R, and G wires (aka all the wires I connected). I tripled checked that they are in there securely, I trimmed the ends of the wires so there's fresh copper, and the Thermostat is seated properly.

I am at an utter loss. Please help.

Re: Error M20/E298

Patrick_Caezza — Sun, 29 May 2022 04:53:19 GMT

Post a picture of the original thermostat's wiring here.

Is this a heat-only system? Is it a boiler, furnace, or something else?

With only the W, R, and G wire, the Google Nest Thermostat needs the C wire installed. Depending on the type of heating system that you have, you might need to also install an external 24VAC transformer with the Nest Power Connector.

Re: Error M20/E298

Chergirl9 — Sun, 29 May 2022 05:29:18 GMT

This is my original wiring. It is a heat-only system.

I did connect the c-wire power connector to my furnace's control board.

Re: Error M20/E298

Patrick_Caezza — Mon, 30 May 2022 05:37:34 GMT

Your wiring looks just fine.

What is your heat source? Boiler, furnace?

How did you wire the Power Connector to the heat source?

Re: Error M20/E298

MelbaDT — Fri, 10 Jun 2022 01:07:29 GMT

Hey folks,

Appreciate your help, Patrick_Caezza.

Chergirl9, I'm jumping in to ensure everything is good here. Have you've seen Patrick's last response? Let us know of the answers so we could take a closer look at them.

Best,

Melba

Re: Error M20/E298

MelbaDT — Tue, 14 Jun 2022 03:46:04 GMT

Hey Chergirl9,

How's it going with your thermostat? Still need our help?

Melba