2002 Kia Optima P0123 code

Measure the voltages on the TPS by back-probing through the rubber seals in the connector. The voltages have to be taken with the connector plugged in to be valid. You must find 5.0 volts on the feed wire, 0.2 volts on the ground wire, and between 0.5 and 4.5 volts on the signal wire, depending on throttle position from idle to wide-open-throttle.

To read 100 percent, you have to have 5.0 volts on the signal wire which will set that fault code. The ground wire has to be open or the signal wire is open. If it comes to that, you'll need to use a scanner to view live data to compare the actual reading on the signal wire to what the computer is seeing.