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Navien Error Codes — What They Mean & What to Do
Your Navien is giving you a code on purpose. It's telling you something specific. Clearing the code without fixing the cause will put you back here next month.
Johnson Bros. — licensed MA master plumber, Navien service specialist. Quincy & Abington offices.
Common Navien Error Codes
Quick reference — what each code points to. Click the highlighted codes for deeper dives.
Most common startup fault. Gas valve, flame rod, venting, or low gas pressure.
Flame detected when it should not be. Usually a flame rod or ignition module issue.
Unit ignited but lost flame. Flame rod, gas pressure, or combustion air.
Scale buildup or reduced water flow through the heat exchanger. Usually a descale.
Sensor or wiring fault. Straightforward diagnostic and part replacement.
Exhaust sensor fault. Replace sensor, verify venting.
Low supply pressure. Often a gas-line sizing issue, not a unit failure.
Inlet filter clog, scale restriction, or valve issue.
Blower motor, RPM sensor, or wiring.
Venting obstruction, damper, or pressure switch.
Control board communication fault. Often a wiring or board issue.
Internal recirc pump or sensor (NPE-A2 models with built-in recirc).
How to Read Your Navien Display
- 1. Look at the front panel. The error code shows as an "E" followed by a 3-digit number (e.g., E003). Some codes start with "A" for air or "P" for pump.
- 2. Write it down exactly. "E003" vs "E030" point to very different issues.
- 3. Note the conditions: did it error on startup, during a shower, after a long idle, during a freeze? Context matters.
- 4. One reset attempt is fine — power off at the disconnect, wait 30 seconds, power back on. If it clears and stays clear, great. If it comes back, stop resetting and call.
- 5. Call (617) 479-9911 with the code and context. We'll tell you whether this is a same-day call or a standard-schedule diagnostic.
Common Questions About Navien Error Codes
Why South Shore homeowners choose Johnson Bros.
Your Navien has an error code — what's next?
Tell us the code and what the unit is doing. We'll triage and tell you whether it's an emergency, a same-day call, or a scheduled diagnostic.
Need help fast? Call for urgent plumbing issues. Booking online is best when you want the next open appointment without waiting on the phone.
How We Work
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Repair-First Guidance
We help you understand whether repair, replacement, or follow-up service makes the most sense.
Your Navien has an error code — what's next?
Tell us the code and what the unit is doing. We'll triage and tell you whether it's an emergency, a same-day call, or a scheduled diagnostic.
Call for urgent help now. Book online when you want the next available fit for your schedule.