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A.O. Smith · ATI-540H-N 0.54 GPM 199,900 BTU High Efficiency Tankless Gas Water Heater

A.O. Smith ATI-540H-N 0.54 GPM 199,900 BTU High Efficiency Tankless Gas Water Heater 41 Error Fix: Fan Speed Abnormal

The combustion fan (blower) speed is not within the normal operating range. The fan may be running too fast, too slow, or erratically. Check for obstructions in the exhaust vent that could create back pressure. Inspect the fan blades for debris or damage. Check the fan motor wire connections. If the vent system is correct and the motor connections are good, the fan motor or the control board may need replacement.

Medium severity2 fixes available✨ Free fix available

Quick Answer

Error 41 on the A.O. Smith ATI-540H-N 0.54 GPM 199,900 BTU High Efficiency Tankless Gas Water Heater means: Fan Speed Abnormal. The top-ranked community fix is “Test and Replace the Combustion Fan Motor or Control Board” (hard difficulty, ~60 min, DIY cost: $5-$20). 2 community-ranked fixes available below.

Published February 2026 · 2 fixes · water heater

Content is based on manufacturer service documentation, community repair experience, and OEM technical bulletins. Always verify with your owner's manual.Learn about our editorial standards.

When to Call a Professional

While many water heater repairs can be done safely at home, consider hiring a qualified technician if:

The repair involves electrical wiring, gas lines, or refrigerant
You've tried the top-ranked fix and the error persists
You smell gas, see sparking, or notice water leaking
The repair requires specialized tools you don't have
Your appliance is still under manufacturer warranty

Average professional repair cost for this issue: $300-$450.

Other A.O. Smith Models with Error 41

GT15-340-NI Commercial 340,000 BTU Commercial Natural Gas Water Heater

water_heater · 2 fixes

Other A.O. Smith ATI-540H-N 0.54 GPM 199,900 BTU High Efficiency Tankless Gas Water Heater Error Codes

Ignition Failure

2 fixes

Flame Failure

2 fixes

Combustion Abnormality

2 fixes

Overheat Protection Activated

2 fixes

Over-Temperature Warning

2 fixes

Reversed Polarity / Neutral-Ground Cross

2 fixes

Inlet Water Temperature Sensor Failure

2 fixes

Outlet Water Temperature Sensor Failure

2 fixes

People Also Ask About A.O. Smith ATI-540H-N 0.54 GPM 199,900 BTU High Efficiency Tankless Gas Water Heater Error 41

What does error code 41 mean on a A.O. Smith ATI-540H-N 0.54 GPM 199,900 BTU High Efficiency Tankless Gas Water Heater?

Error code 41 on the A.O. Smith ATI-540H-N 0.54 GPM 199,900 BTU High Efficiency Tankless Gas Water Heater means: Fan Speed Abnormal. The combustion fan (blower) speed is not within the normal operating range. The fan may be running too fast, too slow, or erratically. Check for obstructions in the exhaust vent that could create back pressure. Inspect the fan blades for debris or damage. Check the fan motor wire connections. If the vent system is correct and the motor connections are good, the fan motor or the control board may need replacement.

How do I fix error code 41 on my A.O. Smith ATI-540H-N 0.54 GPM 199,900 BTU High Efficiency Tankless Gas Water Heater?

The most successful fix is "Test and Replace the Combustion Fan Motor or Control Board" (hard difficulty, ~60 minutes). Estimated DIY cost: $5-$20. HomeMD has 2 community-ranked fixes for this error.

Is error code 41 on a A.O. Smith ATI-540H-N 0.54 GPM 199,900 BTU High Efficiency Tankless Gas Water Heater serious?

This error is rated medium severity. It should be addressed soon, but your appliance may still function in a limited capacity.

Can I fix A.O. Smith ATI-540H-N 0.54 GPM 199,900 BTU High Efficiency Tankless Gas Water Heater error 41 myself?

Yes — the top-ranked community fix ("Test and Replace the Combustion Fan Motor or Control Board") is rated hard difficulty and takes about 60 minutes. Tools needed: T20 Torx screwdriver, Multimeter, Nut driver set.

How much does it cost to repair A.O. Smith ATI-540H-N 0.54 GPM 199,900 BTU High Efficiency Tankless Gas Water Heater error 41?

DIY cost: $5-$20. Professional repair typically costs $300-$450. Many homeowners save money by trying the top-ranked community fix first.

What other error codes does the A.O. Smith ATI-540H-N 0.54 GPM 199,900 BTU High Efficiency Tankless Gas Water Heater have?

The A.O. Smith ATI-540H-N 0.54 GPM 199,900 BTU High Efficiency Tankless Gas Water Heater has 8 other known error codes, including: 11 (Ignition Failure), 12 (Flame Failure), 13 (Combustion Abnormality), 14 (Overheat Protection Activated), 16 (Over-Temperature Warning), and 3 more.

Which other A.O. Smith models have the 41 error?

Error code 41 also appears on 1 other A.O. Smith model: GT15-340-NI Commercial 340,000 BTU Commercial Natural Gas Water Heater. The fix may vary by model, so check each model's specific page for tailored repair steps.

What other error codes does the A.O. Smith ATI-540H-N 0.54 GPM 199,900 BTU High Efficiency Tankless Gas Water Heater have?

The A.O. Smith ATI-540H-N 0.54 GPM 199,900 BTU High Efficiency Tankless Gas Water Heater has 8 other known error codes:

11 — Ignition Failure (2 fixes)
12 — Flame Failure (2 fixes)
13 — Combustion Abnormality (2 fixes)
14 — Overheat Protection Activated (2 fixes)
16 — Over-Temperature Warning (2 fixes)
29 — Reversed Polarity / Neutral-Ground Cross (2 fixes)
31 — Inlet Water Temperature Sensor Failure (2 fixes)
32 — Outlet Water Temperature Sensor Failure (2 fixes)

Which other A.O. Smith models have the 41 error?

Error code 41 also appears on 1 other A.O. Smith model:

GT15-340-NI Commercial 340,000 BTU Commercial Natural Gas Water Heater (water heater) · 2 fixes

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