Amana Washer Error Code OP

The OP error code on an Amana washer indicates that the thermistor in the water mixing valve is reading temperatures below 10°F, or that the thermistor circuit is open. The thermistor is a temperature-sensing resistor embedded in or near the water mixing valve that monitors incoming water temperature. When the control board receives a resistance value outside the expected range, specifically one that corresponds to an open circuit or an extremely low temperature reading, it triggers the OP fault and halts normal operation to prevent potential damage or incorrect cycle behavior.

The most common cause of this code is not actually a freezing condition, but rather a wiring or connection failure between the thermistor and the control board. An open circuit, caused by a broken wire, a corroded connector, or a thermistor that has failed internally, will produce the same resistance signal as an impossibly low temperature. Because of this, the diagnostic process begins at the thermistor connection point in the water mixing valve, checking that the harness is fully seated and free of corrosion or damage.

If the connections are intact, the thermistor itself should be tested for proper resistance using a multimeter. A thermistor that reads infinite resistance (open loop) or a value far outside the normal operating range needs to be replaced. In rare cases involving machines stored or installed in unheated spaces, actual near-freezing inlet water temperatures could legitimately trigger this code, but this scenario is uncommon in normal household installations.