EMERGENCY CALLS AROUND THE CLOCK
CLICK TO TALK TO A REAL PLUMBERTAP TO CALL NOW
Navien Error Code E004
False flame detection — the unit sees a flame signal when there should not be one.
E004 is the opposite of the failure most people expect. Instead of failing to light, the unit is reporting a flame signal at a moment when the burner should be off. The control board treats that as a safety problem and locks out, because a burner it cannot positively confirm is off is a burner it cannot control.
What causes E004
1. A dirty or wet flame rod
The flame sensing rod reads a tiny current through the flame. Soot, corrosion or condensate on the rod or its lead can produce a reading with no flame present. This is the most common cause and is resolved by cleaning or replacing the rod.
2. A gas valve not fully closing
If the valve seeps, a small flame can persist after shutdown and the board correctly reports it. This one is not a wait-and-see item — it is a live gas fault and needs a plumber the same day.
3. Condensate or moisture in the burner area
Condensing units make acidic water by design. If the condensate path is blocked, moisture ends up where the sensing circuit lives and produces false readings alongside other odd codes.
4. A failing control board or wiring fault
Less common. A chafed harness or a board fault can present the same way, which is why the sensing circuit gets tested before anything is replaced.
What you can safely check first
- Power the unit off at the disconnect, wait thirty seconds, and power it back on. One reset is reasonable.
- Check whether you can smell gas anywhere near the unit. If you can, leave the area and call the gas utility or 911 first — not us.
- Look for water pooling under or around the unit, which points at the condensate path.
When to stop and call us
If E004 comes back after one reset, stop there. This code can indicate a gas valve that is not closing fully, and repeatedly resetting a unit that reports an uncommanded flame is not a risk worth taking.
Seeing E004 on your Navien?
Book online and we will diagnose the actual cause, explain what we find, and price the repair before starting.
Navien E004 FAQs
What does Navien error code E004 mean?
It means false flame detection. The control board is reading a flame signal when the burner should be off, so it locks the unit out as a safety response. It is usually a dirty flame rod, but it can indicate a gas valve that is not closing.
Is E004 dangerous?
Treat it seriously. Most E004s are a dirty sensing rod, which is harmless in itself, but the same code appears when a gas valve seeps. Because you cannot tell which from the display, one reset is reasonable and a repeat means call a licensed plumber.
Can I fix E004 myself?
You can safely try one power cycle and check for standing water or a gas smell. Cleaning the flame rod means opening the sealed combustion area, which is a licensed job on a gas appliance and is not a homeowner repair.
How much does an E004 repair cost?
Our $99 service fee applies toward the repair, and you get an upfront price before any work starts. Most E004s are resolved by cleaning or replacing a sensing rod rather than a major part, which keeps it predictable.
Other codes on this unit? See all Navien error codes.
Why South Shore homeowners choose Johnson Bros.
Navien E004 diagnosed properly
We diagnose the cause rather than clearing the code and hoping. You get an upfront price before any work starts.
Not sure what's wrong? Send a photo or videoBooking online is the quickest way to hold the next open appointment. Call instead if it is urgent and you would rather talk to someone.
Can't talk right now? Get a callback.
Related services
All Navien error codes
The other codes this unit can show, and what each one means.
Navien service and repair
Installation, service and repair for Navien equipment on the South Shore.
Family Plan
Annual maintenance is what prevents most of these codes. Members receive service fee waived when approved work is completed and 10% off.
How We Work
Clear communication, licensed work, and local support.
Licensed Plumbing Work
Massachusetts-licensed plumbing support backed by insured crews.
Fast Scheduling Updates
We tell you what timing is available and keep you updated if the schedule shifts.
Upfront Options
You get a clear explanation of the work and price before the job begins.
Repair-First Guidance
We help you understand whether repair, replacement, or follow-up service makes the most sense.
Navien E004 diagnosed properly
We diagnose the cause rather than clearing the code and hoping. You get an upfront price before any work starts.
Call for urgent help now. Book online when you want the next available fit for your schedule.