The 7 Most Common Nest Thermostat Error Codes (2025 Guide): Fixes, Costs & Expert Tips

Your Nest thermostat simplifies home comfort—until an error code appears. These cryptic messages can leave you confused, sweating, or shivering.
We’ve compiled the 7 most frequent Nest thermostat error codes with simple fixes, cost estimates, and proven strategies to restore your system fast.
Quick Reference: Nest Thermostat Error Codes
Error Code | Severity | Common Causes | Quick Fix |
---|---|---|---|
E298 | Critical | Power loss | Check wiring/breakers 110 |
E294 | Critical | R-wire misconfigured | Factory reset/reconfigure wiring 35 |
E195 | Critical | HVAC overheating | Check AC filter/drainage 110 |
E103/E104 | Critical | Electrical overload | Turn off power; call a pro 13 |
N260 | Non-critical | Missing C-wire | Install C-wire/Power Connector 510 |
E73 | Critical | Rc wire no power | Inspect wiring/breakers 310 |
1. E298: Critical Power Loss110
What it means: Your Nest thermostat has lost main power and switched to its backup battery.
Why it happens:
- Tripped circuit breaker or blown fuse.
- Loose/damaged wiring (common in newer Nest models).
- Faulty HVAC system switch.
Step-by-step fix:
- Check your breaker box: Flip tripped breakers to “ON.”
- Inspect wiring: Turn off power, then ensure all wires are tightly connected to the thermostat base.
- Test the HVAC switch: Verify the system’s power switch (near the furnace/air handler) is on.
Pro Tip: If the error persists, use a multimeter to test voltage at the thermostat base (24V is normal).
Cost to fix: 75–75–150 (electrician fees for wiring repairs).
2. E294: R-Wire Configuration Error35
What it means: The R-wire (power wire) isn’t properly connected or configured.
Why it happens:
- Incorrect wiring during installation.
- Corrosion or wear on the R-wire connector.
Step-by-step fix:
- Factory reset: Go to Settings > Reset > Factory Reset on your Nest.
- Reconfigure wiring:
- Turn off power.
- Remove the thermostat display.
- Ensure the R-wire has ⅜ inch (6mm) of exposed copper and is fully inserted.
- Update wiring in the app: Use the Nest app to re-scan your wiring setup.
Expert Insight: Older homes often have mismatched Rc/Rh wires. Use a jumper wire if your system requires it.
3. E195: HVAC Overheating110
What it means: Your HVAC system has shut down due to extreme heat, starving the Nest of power.
Why it happens:
- Clogged air filters blocking airflow.
- Frozen evaporator coils or blocked drainage.
Step-by-step fix:
- Replace air filters: Dirty filters cause 80% of overheating issues.
- Clear drainage lines: Pour a 50/50 mix of vinegar and water into the condensate drain.
- Recharge the Nest: Detach the thermostat and charge it via USB for 2 hours.
Cost to fix: 0(DIY)to0(DIY)to200 (professional AC tune-up).
4. E103/E104: Electrical Overload13
What it means: Your thermostat detects dangerous power surges (fire risk).
Why it happens:
- Faulty HVAC control board.
- Short circuits in wiring.
Immediate action:
- Turn off power at the breaker.
- Call a licensed electrician—do NOT attempt DIY fixes.
2025 Update: Google now partners with HVAC pros for same-day E103/E104 repairs in select cities.
5. N260: Missing C-Wire510
What it means: Your Nest lacks a continuous power source (common wire).
Why it happens:
- Older HVAC systems without C-wire compatibility.
Step-by-step fix:
- Check for a C-wire: Remove the thermostat and look for a blue/black wire labeled “C.”
- Install a Nest Power Connector: A $25 adapter that mimics a C-wire (requires wiring to HVAC).
Pro Tip: Systems without C-wires drain Nest batteries faster. Add a Power Connector to prevent recurring issues.
6. E73: No Power to Rc Wire310
What it means: The Rc wire (cooling power) isn’t delivering electricity.
Why it happens:
- Tripped breaker for AC unit.
- Loose Rc wire connection.
Step-by-step fix:
- Reset the AC breaker.
- Tighten the Rc wire: Ensure ⅜ inch of exposed copper is secured in the connector.
Cost to fix: 0(DIY)to0(DIY)to120 (if HVAC pro replaces damaged wires).
Preventing Nest Thermostat Errors: 3 Expert Tips
- Schedule annual HVAC maintenance to avoid overheating and electrical faults.
- Install surge protectors to shield your Nest from power spikes.
- Use the Nest app’s Health Report for early warnings about wiring issues.
FAQ: Nest Error Code Solutions
Q: Can I ignore non-critical codes like N260?
A: Temporarily, but long-term power issues may damage your thermostat.
Q: Why does my Nest show E195 only in summer?
A: High temperatures strain HVAC systems, triggering safety shut-offs. Clean filters monthly in hot weather.
Q: Are Nest repairs covered under warranty?
A: Google’s 2-year warranty covers defects, not installation errors.
Final Thoughts
Nest error codes are warning signs, not dead ends. With this guide, you can troubleshoot most issues in under 30 minutes. For critical codes like E103/E104, always prioritize safety—turn off power and call a pro. Stay ahead of problems with routine HVAC care, and your Nest will keep your home comfortable for years.
Need Help Now? Book a certified Nest Pro through Google Home Services for same-day fixes in 2025.

I’m Alan William’s, the founder of SmartHeatSolution.com. I am from California, USA, I’m passionate about innovative heating technologies and their impact on our homes and businesses. With a background in electrican and home repair , I aim to make smart, energy-efficient heating accessible to everyone. When I’m not writing, I’m likely interested in all the thermostat brands and their new technnology. Thanks for stopping by!