A.O. Smith fault code C04
Fault code C04 on an A.O. Smith water heater (including ADMR) means: Wrong appliance selection / selection resistor. Reset the appliance once. If the code comes back, a part is usually faulty. You can check the water pressure and settings yourself; leave work on gas-carrying parts to a certified gas engineer.
After a safety alert (gas, flue gas, combustion), reset no more than once and call in a certified gas engineer. If you smell gas, call your national gas emergency number or 112 immediately.
Cause
Fault code C04 on an A.O. Smith water heater indicates: Wrong appliance selection / selection resistor.
Applies to
A.O. Smith ADMR, 115, 135, 40, 50, 60, 80, 90.
Fault code C04 on other A.O. Smith series
The same code does not mean the same thing on every series. Check the rating plate to see which series you have:
- C04 on Innovo, IR 12-160, IR 12-200, IR 20-160, IR 20-200, IR 24-245: Control fault: This occurs when the control and/or the display has been replaced. Incorrect selection of the boiler.
- C04 on BFC, 100, 120, 28, 30, 50: Appliance selection error: Wrong appliance selection / selection resistor.
Matching parts
A.O. Smith parts are available from Instalpunt; shipping to EU countries from €17.95 (€24.95 for more distant countries), usually 3–5 working days.
This message does not point directly to one faulty part. These are the parts that most often fit this appliance:
- A.O. Smith anode 3/4" € 47.04
- A.O. Smith service gasket manhole € 56.19
- A.O. Smith sensor NTC assy € 57.50
Fix it yourself or call an engineer?
Always consult the manual for your appliance and work safely. If in doubt or if the fault comes back, call in a qualified professional. A question about a part? Write to us at info@instalpunt.nl.
Frequently asked questions
What does A.O. Smith water heater fault code C04 mean?
Wrong appliance selection / selection resistor.
How do I fix fault code C04 on an A.O. Smith water heater?
First check the cause described above. Then restart the appliance using the reset button. If the message comes back, a part usually needs replacing or the fault needs to be repaired by a qualified professional.
Which parts do I need for A.O. Smith fault code C04?
That depends on the exact cause. In the A.O. Smith parts overview at Instalpunt you will find the current price and stock for each part.
Can I fix fault code C04 myself?
You can reset the appliance and check things like the water pressure or settings yourself. Work on gas-carrying parts must be left to a certified gas engineer.
All A.O. Smith water heater faults and codes at a glance →