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H157

Google Nest Thermostat H157: Heat Link removed from the app

Verified with sources2 sourcesReviewed Oct 18, 2026
Technician coming? See the 2 steps they must show you
Round smart thermostat mounted on a wall
AG20044018CC BY-SA 4.0Image source

Risk level

Low

Usually safe to check without specialist tools.

Urgency

Medium

Quick answer

Help code H157 appears when you have removed the Heat Link from the app; reconnect it under Settings > Add product and enter the 6-character pairing code printed under the Heat Link cover (or press the Heat Link button for manual heat).

Safety first

Stop and check this first

  • When pulling off the Heat Link cover to read the QR code or the 6-character pairing code near the left screw hole, never touch or move exposed boiler wires; any wiring work requires turning off home power at the fuse box first and should be left to a professional installer.
  • If your Nest Thermostat E Heat Link uses AA batteries and needs new ones, replace them only with new L91 Energizer Lithium AA batteries and never use standard alkaline cells.

Safe checks you can perform

  • Turn heating on or off manually with the Heat Link button while troubleshooting
  • Reset the Heat Link to factory defaults if it cannot connect to the app
  • Re-add the Heat Link in Settings > Add product and enter the 6-character code

Leave these tasks to a qualified professional

  • Do not attempt this professional task: Contact Google Nest support if H157 persists after re-adding the Heat Link
  • Do not attempt this professional task: Have a local Nest Pro inspect the Heat Link if manual heating or boiler power fails

What a technician must be able to justify

Technician visit

These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.

These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.

  1. Contact Google Nest support if H157 persists after re-adding the Heat Link

    What they doGoogle Nest support checks the account binding and pairing state of your Heat Link and thermostat when Settings > Add product and the 6-character code do not clear H157.

    They must show youthe Heat Link status light color (solid yellow, pulsing blue, or green) and the 6-character pairing code found under the front cover.

    In writingthe Google Nest support ticket reference, the pairing check result for your account, and any warranty replacement instructions.

  2. Have a local Nest Pro inspect the Heat Link if manual heating or boiler power fails

    What they doA qualified Nest Pro inspects the Heat Link power supply, distance from the boiler, and boiler control terminals if manual heating also fails to respond.

    They must show youthe manual heating button test showing a green light on the Heat Link and the wireless connection test under Settings > Equipment > Heat Link > Test.

    In writingthe written heating system and Heat Link diagnostic report detailing any power or boiler control adjustments made.

Before accepting a part or repair

Nothing has been shown yet. Do not accept a part swap based on the code alone.

Follow these steps

Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.

  1. Turn heating on or off manually with the Heat Link button while troubleshooting

    No special tools

    Who:
    you, pressing the button on your Heat Link.
    How:
    if you need heat while clearing code H157, press the button on your Heat Link twice for Nest Thermostat E (or once for a 2nd or 3rd gen Nest Learning Thermostat) to toggle heating and hot water manually.
    Result that matters:
    keep your home warm while you reconnect the Heat Link to your thermostat in the app.
    If the heating light on the Heat Link turns green:
    manual heating is active while you finish setup.
    If no light turns on when pressing the Heat Link button:
    check its L91 lithium AA batteries or boiler power supply.
    Evidence to keep:
    note of the Heat Link status light color when pressing the manual heat button.

    Evidence: Troubleshoot Nest thermostat help codes

  2. Reset the Heat Link to factory defaults if it cannot connect to the app

    No special tools

    Who:
    you, holding the button on the Heat Link.
    How:
    if your Heat Link cannot connect to the app directly, press and hold the Heat Link button on Nest Thermostat E until the status light turns solid yellow (about 15 seconds), then release it and wait for the light to pulse blue.
    Result that matters:
    return the Heat Link to factory default settings (pulsing blue light) so it can be added back.
    If the status light pulses blue when the reset finishes:
    proceed to add the Heat Link back in the app.
    If the status light does not pulse blue after holding the button for 15 seconds:
    record the LED behavior for Nest support.
    Evidence to keep:
    photo or note of the Heat Link status light after the 15-second reset hold.

    Evidence: Troubleshoot Nest thermostat help codes

  3. Re-add the Heat Link in Settings > Add product and enter the 6-character code

    No special tools

    Who:
    you, pulling off only the Heat Link front cover without touching wiring.
    How:
    pull off the Heat Link cover to find the QR code above the battery compartment and the 6-character letter-and-number code near the left screw hole; in the app go to Settings > Add product and enter the 6-character pairing code on the thermostat display when prompted.
    Result that matters:
    reconnect the Heat Link to your Nest thermostat and app account.
    If pairing finishes and help code H157 disappears from the thermostat display:
    verify normal temperature control.
    If you followed all steps above and still get H157 on your thermostat:
    contact Nest support for more help.
    Evidence to keep:
    photo of the 6-character pairing code near the left screw hole and app setup screen.

    Evidence: Troubleshoot Nest thermostat help codes

Still not solved

If the error persists, stop here. See what the technician must do and show you.

Where this code applies

A code is meaningful only inside the right product and version context.

Primary scope

System
HVAC
Brand
Google Nest
Product type
Smart thermostats

Known code variants

  • Código H157
  • Error H157
  • H157 code
  • H157 Nest Thermostat E
  • Heat Link eliminado de la aplicación
  • Heat Link removed from the app
  • Nest Thermostat E H157

What it means

On Google's official help codes page for Nest thermostats controlling European condensing boilers, OpenTherm systems, domestic hot water tanks, district heating, or fil pilote setups, code H157 applies to the Nest Thermostat E (2nd and 3rd generation Nest Learning Thermostats use different button hold durations). It appears when the Heat Link has been removed from the app while the thermostat remains active. Seeing H157 alone never proves that the Heat Link or thermostat hardware is defective: it means the app pairing was removed and must be restored.

Warnings and stop conditions

  • Higheditorial warning

    When pulling off the Heat Link cover to read the QR code or the 6-character pairing code near the left screw hole, never touch or move exposed boiler wires; any wiring work requires turning off home power at the fuse box first and should be left to a professional installer.

    Evidence: Troubleshoot Nest thermostat help codes

  • Loweditorial warning

    If your Nest Thermostat E Heat Link uses AA batteries and needs new ones, replace them only with new L91 Energizer Lithium AA batteries and never use standard alkaline cells.

    Evidence: Troubleshoot Nest thermostat help codes

Symptoms and causes

Probable causes · in order

  • Heat Link removed from the account inside the Nest appCommon

    Someone with access to the home account removed the Heat Link in the app settings, leaving the thermostat unable to send scheduled heating commands to the receiver.

    Evidence: Troubleshoot Nest thermostat help codes

  • Heat Link factory reset completed without re-adding it in the appPossible

    Resetting the Heat Link for Nest Thermostat E to factory defaults automatically removes it from the app and requires setting it up again from scratch under Add product.

    Evidence: Troubleshoot Nest thermostat help codes

  • Six-character Heat Link pairing code not yet entered on the thermostatPossible

    During reconnection, the Nest thermostat display may wait for the 6-character alphanumeric pairing code printed near the left screw hole under the Heat Link cover.

    Evidence: Troubleshoot Nest thermostat help codes

Virtual technician

Does H157 still appear after these checks?

Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.

Start diagnosis

Sources and technical references

  1. 1

    Troubleshoot Nest thermostat help codes

    Google · 2026 · official_doc

  2. 2

    Códigos de error de los termostatos Nest y solución de problemas

    Google · 2026 · official_doc

Sources: Troubleshoot Nest thermostat help codes · Códigos de error de los termostatos Nest y solución de problemasreviewed 2026-10-18 · verified

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