OEM, 'genuine', and aftermarket parts: real risks, what warranty law says, and how to choose on a service call

OEM (the part the appliance maker specifies under its part number) is the safe default for anything electrical, safety-related, water-carrying or controlled by firmware: boards, sensors, gas or water valves, thermal fuses and limits, door locks, and water filters. Aftermarket parts can be fine for simple mechanical items when they match the OEM part's specs, but fit and quality vary and you carry the callback. Counterfeit refrigerator water filters are a documented problem: in AHAM-sponsored lab tests most failed to remove lead and cysts for their labeled life and some leached chemicals. Under federal warranty law, a maker generally cannot void a warranty just because a non-brand part or independent service was used, but it can deny coverage for damage that part caused.

Cross-checked ~10 min easyBrands: All

Before you start

Never install a non-listed part on a gas control, thermal limit or other safety device
Do not install water filters that are not certified (at least NSF/ANSI 42) for the model; counterfeits can leak or add contaminants

Diagnostic steps

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