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8 Flashes

A.O. Smith · GCR-40 ProLine 40 Gal 38,000 BTU ProLine Gas Water Heater with Energy Saver

A.O. Smith GCR-40 ProLine 40 Gal 38,000 BTU ProLine Gas Water Heater with Energy Saver 8 Flashes Error Fix: Loss of Pilot Signal

The gas control valve lost the pilot signal (thermopile voltage) during main burner operation. This can indicate an intermittent thermopile connection, a draft blowing out the pilot flame, or a failing thermopile that works initially but cannot sustain voltage under load. Check for drafts near the water heater combustion chamber. Inspect the pilot tube for blockage. Verify the thermopile connections are secure. If the pilot flame is unstable or yellow, clean the pilot assembly and check the air intake.

High severity2 fixes available

Quick Answer

Error 8 Flashes on the A.O. Smith GCR-40 ProLine 40 Gal 38,000 BTU ProLine Gas Water Heater with Energy Saver means: Loss of Pilot Signal. The top-ranked community fix is “Test and Replace Thermopile Sensor” (medium difficulty, ~45 min, DIY cost: $10-$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:

This is a high severity error — continued use may cause damage or a safety hazard
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: $150-$250.

Other A.O. Smith Models with Error 8 Flashes

GNVR-50 ProMax Gas 50 Gal 40,000 BTU ProMax Gas Water Heater with Electronic Ignition

water_heater · 2 fixes

GPVL-50 ProLine XE 50 Gal 38,000 BTU ProLine XE Power Vent Gas Water Heater

water_heater · 2 fixes

GPVT-50 Power Vent 50 Gal 38,000 BTU Power Vent Gas Water Heater with Electronic Ignition

water_heater · 2 fixes

Other A.O. Smith GCR-40 ProLine 40 Gal 38,000 BTU ProLine Gas Water Heater with Energy Saver Error Codes

1 Flash

Normal Operation

2 fixes

2 Flashes

Thermopile Voltage Low

2 fixes

4 Flashes

Temperature Exceeded High Limit

2 fixes

5 Flashes

Temperature Sensor Failure

2 fixes

7 Flashes

Gas Control Valve Failure

2 fixes

People Also Ask About A.O. Smith GCR-40 ProLine 40 Gal 38,000 BTU ProLine Gas Water Heater with Energy Saver Error 8 Flashes

What does error code 8 Flashes mean on a A.O. Smith GCR-40 ProLine 40 Gal 38,000 BTU ProLine Gas Water Heater with Energy Saver?

Error code 8 Flashes on the A.O. Smith GCR-40 ProLine 40 Gal 38,000 BTU ProLine Gas Water Heater with Energy Saver means: Loss of Pilot Signal. The gas control valve lost the pilot signal (thermopile voltage) during main burner operation. This can indicate an intermittent thermopile connection, a draft blowing out the pilot flame, or a failing thermopile that works initially but cannot sustain voltage under load. Check for drafts near the water heater combustion chamber. Inspect the pilot tube for blockage. Verify the thermopile connections are secure. If the pilot flame is unstable or yellow, clean the pilot assembly and check the air intake.

How do I fix error code 8 Flashes on my A.O. Smith GCR-40 ProLine 40 Gal 38,000 BTU ProLine Gas Water Heater with Energy Saver?

The most successful fix is "Test and Replace Thermopile Sensor" (medium difficulty, ~45 minutes). Estimated DIY cost: $10-$20. HomeMD has 2 community-ranked fixes for this error.

Is error code 8 Flashes on a A.O. Smith GCR-40 ProLine 40 Gal 38,000 BTU ProLine Gas Water Heater with Energy Saver serious?

This error is rated high severity. You should address it promptly — continued use could cause damage or safety concerns.

Can I fix A.O. Smith GCR-40 ProLine 40 Gal 38,000 BTU ProLine Gas Water Heater with Energy Saver error 8 Flashes myself?

Yes — the top-ranked community fix ("Test and Replace Thermopile Sensor") is rated medium difficulty and takes about 45 minutes. Tools needed: T20 Torx screwdriver, Multimeter, Adjustable wrench.

How much does it cost to repair A.O. Smith GCR-40 ProLine 40 Gal 38,000 BTU ProLine Gas Water Heater with Energy Saver error 8 Flashes?

DIY cost: $10-$20. Professional repair typically costs $150-$250. Many homeowners save money by trying the top-ranked community fix first.

What other error codes does the A.O. Smith GCR-40 ProLine 40 Gal 38,000 BTU ProLine Gas Water Heater with Energy Saver have?

The A.O. Smith GCR-40 ProLine 40 Gal 38,000 BTU ProLine Gas Water Heater with Energy Saver has 5 other known error codes, including: 1 Flash (Normal Operation), 2 Flashes (Thermopile Voltage Low), 4 Flashes (Temperature Exceeded High Limit), 5 Flashes (Temperature Sensor Failure), 7 Flashes (Gas Control Valve Failure).

Which other A.O. Smith models have the 8 Flashes error?

Error code 8 Flashes also appears on 3 other A.O. Smith models: GNVR-50 ProMax Gas 50 Gal 40,000 BTU ProMax Gas Water Heater with Electronic Ignition, GPVL-50 ProLine XE 50 Gal 38,000 BTU ProLine XE Power Vent Gas Water Heater, GPVT-50 Power Vent 50 Gal 38,000 BTU Power Vent Gas Water Heater with Electronic Ignition. 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 GCR-40 ProLine 40 Gal 38,000 BTU ProLine Gas Water Heater with Energy Saver have?

The A.O. Smith GCR-40 ProLine 40 Gal 38,000 BTU ProLine Gas Water Heater with Energy Saver has 5 other known error codes:

1 Flash — Normal Operation (2 fixes)
2 Flashes — Thermopile Voltage Low (2 fixes)
4 Flashes — Temperature Exceeded High Limit (2 fixes)
5 Flashes — Temperature Sensor Failure (2 fixes)
7 Flashes — Gas Control Valve Failure (2 fixes)

Which other A.O. Smith models have the 8 Flashes error?

Error code 8 Flashes also appears on 3 other A.O. Smith models:

GNVR-50 ProMax Gas 50 Gal 40,000 BTU ProMax Gas Water Heater with Electronic Ignition (water heater) · 2 fixes
GPVL-50 ProLine XE 50 Gal 38,000 BTU ProLine XE Power Vent Gas Water Heater (water heater) · 2 fixes
GPVT-50 Power Vent 50 Gal 38,000 BTU Power Vent Gas Water Heater with Electronic Ignition (water heater) · 2 fixes

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