Weil-McLain A57 Error Code — What It Means
The exact meaning of an A57 code on a Weil-McLain boiler is not confirmed by manufacturer documentation and depends entirely on your specific model and control platform. Weil-McLain produces multiple boiler lines (CGi, Ultra, EG, and others), each with its own control board and fault-code library. A code displayed as A57 may be a control history entry, an accessory fault, or a sensor alarm on certain models, but without the precise model number and control manual you cannot reliably determine what component or condition triggered it.
Weil-McLain’s own technical guidance directs contractors to use the boiler’s model and serial (CP) number to retrieve the correct service documentation and fault-code table before diagnosing or ordering parts. Attempting to repair based on guesswork or forum posts risks replacing the wrong component. Locate the rating plate on your boiler, note the full model designation and CP number, then consult the matching installation and service manual or contact Weil-McLain technical support with that information to confirm what A57 means for your unit.
Before You Replace Anything
Technicians sometimes replace control boards or sensors without first identifying the exact fault definition for their model, wasting hundreds of dollars. Always retrieve the full fault history from the control and match the code to the model-specific manual before ordering any part.
Common Causes
- Unknown model-specific fault (~100%) A57 is not a universal Weil-McLain code, so the cause depends entirely on which control platform and boiler series you own.
Quick Diagnosis
Answer these to narrow it down fast.
Do you have the boiler's full model number and CP number from the rating plate?
No: Locate the metal rating plate (usually on the front jacket or inside the burner door) and record both numbers before proceeding.
Does your control display a longer fault description or additional codes in the history menu?
No: The control may require a specific button sequence to enter diagnostic mode and view extended fault data, consult the manual for the unlock procedure.
Is the boiler currently running or is it locked out?
No: A lockout condition means the control has shut down the burner for safety, do not reset repeatedly without diagnosing the root cause first.
Step-by-Step Fix
- Record the boiler model and CP number from the rating plate (usually on the front panel or inside the burner-access door).
- Access the control’s fault-history menu using the procedure in your installation manual (often a sequence of button presses or a service key).
- Write down all active and logged fault codes including timestamps, so you can see if A57 appeared alone or alongside other faults.
- Retrieve the correct service manual for your model from Weil-McLain’s website, your installer, or by calling Weil-McLain technical support with the model and CP number.
- Look up code A57 in the fault-code table of that manual to confirm the exact component, sensor, or condition it represents.
- Perform the diagnostic checks listed in the manual for that fault (resistance tests, voltage checks, or visual inspection of the named component).
- Replace or repair the identified component following the manual’s procedures, then clear the fault history and verify normal operation before leaving the boiler unattended.
Parts Often Needed
| Part | Notes |
|---|---|
| Control board (model-specific) | Amazon | Only if diagnostics confirm board failure; order by exact boiler model and CP number. |
| Sensor or switch (model-specific) | Amazon | The manual will name the sensor tied to A57 on your model; verify resistance before replacing. |
When to Call a Pro
Call a licensed boiler technician or gas fitter if you cannot locate the model documentation, if the fault code table requires electrical measurements (resistance, continuity, or voltage), or if the indicated repair involves gas piping, burner components, or sealed combustion parts. Boilers operate under pressure and involve natural gas or propane, so misdiagnosis or incorrect part replacement can create carbon-monoxide hazards or void your warranty. A qualified technician will have access to Weil-McLain’s technical hotline, the correct service literature, and the test equipment needed to confirm the fault and replace only the failed component.
Rough cost: A pro service call runs about $150-400.