Weil-McLain Boiler A10 Error Code — What It Means
The A10 error code does not appear in Weil-McLain’s official fault code system. Weil-McLain boilers typically use error codes starting with E (for example, E01 for ignition failure, E04 for low water cutoff, E10 for communication fault). If you see A10 on your display, you may be looking at a Vokera or Grant boiler (A10 indicates ignition failure or flame detection issue on those brands), misreading the display (Weil-McLain E10 means communication fault between the system controller and the boiler), or dealing with a third-party controller that is not using Weil-McLain’s native codes.
If your boiler is actually a Vokera unit displaying A10, the control board has locked out after three failed ignition attempts because it could not detect a flame. The most common culprits are a dirty flame sensor coated with soot, a faulty spark electrode, or a blocked air intake preventing the burner from firing. Always verify the exact brand and model of your boiler before troubleshooting, because following the wrong diagnostic path can waste time and money.
Before You Replace Anything
Homeowners often assume A10 is a Weil-McLain code and replace the ignition module or gas valve without first confirming the boiler brand. Check the nameplate on the unit and verify the manufacturer before ordering any parts.
Common Causes
- Misidentified boiler brand (~50%) The unit is actually a Vokera or Grant boiler, not a Weil-McLain, and A10 is Vokera’s ignition failure code.
- Misread error code (~30%) The display shows Weil-McLain E10 (communication fault) but is being read as A10.
- Third-party controller installed (~15%) An aftermarket or incompatible controller is displaying a non-standard fault code.
- Dirty flame sensor (if Vokera) (~5%) If the boiler is confirmed to be a Vokera, soot buildup on the flame sensor prevents flame detection.
Quick Diagnosis
Answer these to narrow it down fast.
Does the boiler nameplate say Vokera or Grant (not Weil-McLain)?
No: Confirm the exact code on the display. If it reads E10, the problem is a communication fault between the system controller and the boiler, not ignition. Consult the Weil-McLain manual for E10 troubleshooting.
Does the display clearly show the letter A (not E) before the 10?
No: The code is likely E10. Check for loose wiring between the system controller and the boiler control board.
Did the code appear after a recent controller or thermostat upgrade?
No: The boiler brand is likely misidentified. Double-check the nameplate and refer to the correct manufacturer's documentation.
Step-by-Step Fix
- Verify the boiler brand by reading the nameplate on the front or side of the unit. Look for the manufacturer name (Weil-McLain, Vokera, Grant, or another brand).
- Confirm the exact error code displayed. Check if it reads A10, E10, or another combination. Take a clear photo if uncertain.
- If the brand is Vokera, turn off the gas and electrical supply, then remove the front cover. Locate the flame sensor (a small probe near the burner) and the spark electrode.
- Clean the flame sensor and spark electrode with a fine abrasive cloth or very fine sandpaper to remove soot and oxidation. Do not force or bend the probes.
- Check the air intake and flue for blockages. Clear any obstructions and verify the air pressure switch connections are secure.
- Restore power and gas, then press the reset button. Observe the ignition sequence. If the burner lights and the code clears, the issue is resolved. If the code returns, the ignition module or flame sensor may need replacement.
- If the brand is Weil-McLain and the code is E10, check for loose wiring between the system controller and the boiler control board. Consult the Weil-McLain manual for E10-specific diagnostics.
Parts Often Needed
| Part | Notes |
|---|---|
| Vokera flame sensor (thermistor) | Amazon | Only if the boiler is confirmed to be a Vokera and cleaning does not resolve A10. |
| Vokera spark electrode | Amazon | Replace if the insulator is cracked or the electrode is damaged. |
When to Call a Pro
Call a qualified heating technician immediately if you cannot confirm the boiler brand, if you are uncomfortable working with gas appliances, or if cleaning the flame sensor and spark electrode does not clear the A10 code on a confirmed Vokera unit. Gas boiler diagnostics require proper tools (multimeters, manometers for gas pressure testing) and safety protocols. If your boiler is a Weil-McLain and displays E10, a technician should inspect the wiring and communication between the system controller and the boiler control board. Misdiagnosing the brand or fault can lead to ordering incorrect parts and creating new safety hazards.
Rough cost: A pro service call runs about $150-300.