What Fault 40 Means
Fault 40 says the controller transistor that drives the ice maker solenoid has failed short. F&P adds the likely reason: a problem in the solenoid itself can take the transistor with it. The procedure is therefore to measure the solenoid and its wiring first, replacing the solenoid if it is out of limits, and to replace the power/control module if everything else checks out.
Common Causes of Fault 40
- A shorted solenoid that has damaged its driving transistor
- A transistor on the control module that has failed short
- Damaged wiring between the module and the solenoid
🔧 One Safe Check You Can Try
Close the water supply valve to the refrigerator while you wait. A failed-short driver is a driver that can no longer be switched off, which is not a state you want a water valve left in.
⚠ Why You Shouldn't Go Further Than That
- Shut the water off and then unplug the appliance before anything is touched, because this is a mains-switched valve on a plumbed connection whose control has failed.
- Fitting a new module without measuring the solenoid risks the replacement transistor failing exactly as the first one did.
- Compression fittings on the fill line seal once, and one re-made by hand weeps slowly behind the cabinet where nobody sees it.
- A driver stuck on can keep a valve energised, so the supply should stay closed until the problem is resolved rather than after.
Opening a panel to inspect or repair something yourself doesn't automatically cancel your manufacturer's warranty — but it can risk accidental damage, and some manufacturers do have specific service conditions. Check your product's warranty terms, or ask us, before deciding.