Kromschroder BCU 46x / 480 Burner Control Unit
Kromschroder BCU 46x / 480 Burner Control Unit code E 04: Blinking E 04
The burner locks out because the flame signal fell below the switch off threshold during normal operation.
Safety first. This code involves a gas, flame or electrical hazard. Do not keep resetting it. Leave burner, gas train and high voltage work to a qualified technician. WERCS answers 24/7 at (877) 489-3727.
- Code
- E 04
- Name
- Blinking E 04
- Controller
- Kromschroder BCU 46x / 480 Burner Control Unit
- Type
- Flame failure
- What it does
- Lockout: the control shuts down and stays off until it is reset
- Risk
- RED Specialist territory
- Reset
- Needs a manual reset
- Source
- The manufacturer's manual (subscribers see which manual and page)
Updated July 23, 2026
How to fix it
Subscribers get:
- What to do next, in plain words
- Which manufacturer manual it comes from, linked
- The 7 common causes listed for this code
- The step by step check for this problem, one check at a time
- Booking a live video call with Ben, a master booth technician ($250/hr, paid per call)
Questions about this code
What does Kromschroder BCU 46x / 480 Burner Control Unit code E 04 mean?
The burner locks out because the flame signal fell below the switch off threshold during normal operation.
Is Kromschroder BCU 46x / 480 Burner Control Unit code E 04 dangerous?
It is graded red, specialist territory: it involves a burner, gas, flame or safety lockout, so leave the repair to a qualified technician.
How do I fix Kromschroder BCU 46x / 480 Burner Control Unit code E 04?
The manual's fix and the step by step check for this code are in WERCS Diagnose, plans from $49 a month. For help right now, WERCS answers 24/7 at (877) 489-3727.
Other Kromschroder BCU 46x / 480 Burner Control Unit codes
53 · Blinking 53Ot · OtUt · UtE 02 · Blinking E 02E 05 · Blinking E 05E 08 · Blinking E 08E 11 · Blinking E 11E 32 · Blinking E 32E 40 · Blinking E 40E 41 · Blinking E 41
All 21 Kromschroder BCU 46x / 480 Burner Control Unit codes · Every fault code