LG Dishwasher Error Code tC

The tC code means the dishwasher's temperature sensor (thermistor) is producing a signal outside the valid voltage range, either above approximately 4.5V or below approximately 0.2V. It can also trigger if water temperature is detected at -3°C or below for 30 seconds while the heater is running. The dishwasher stops operation because it cannot confirm a safe, valid temperature reading. This typically points to a failed thermistor, a bad connection, or damaged wiring.

It is not advisable to continue running the dishwasher while the tC error is active. The control board has halted operation specifically because it cannot monitor water temperature, which means the heating system is running without reliable feedback. Continued use in this condition could result in overheating or inadequate sanitization of dishes.

A power reset by unplugging the dishwasher or turning off the circuit breaker for a few minutes may temporarily clear the tC code, but it will return if the underlying fault is not repaired. The error is triggered by a real out-of-range sensor condition, so resetting without fixing the thermistor, connector, or wiring will only result in the code reappearing once the dishwasher attempts to run a cycle.

A knowledgeable DIYer can address this error by inspecting and reseating the thermistor connector and checking the wiring harness for visible damage. Measuring the thermistor's resistance with a multimeter is also a straightforward test. If the thermistor has failed, replacing it is a moderately accessible repair. However, if the control board is the root cause, professional diagnosis is recommended before purchasing that part.

If only the thermistor needs replacement, parts and labor typically fall in the range of $75 to $175 depending on your location and service provider. If the wiring harness requires repair or replacement, costs may range from $100 to $250. A control board replacement is the most expensive scenario, often ranging from $200 to $400 or more including labor.