what is code P0141 for 2002 highlander failed smog?

Did he even look at it? This is what it is...P0141 TOYOTA - HO2S12 Heater Circuit Malfunction... Possible causes...> - Faulty Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 - Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 circuit fuse - Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 circuit open shorted to ground - Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 circuit poor electrical connection - Faulty Engine Control Module (ECM).. Some Tech notes... The code means that there is a problem with the heater element circuit of the heated oxygen sensor. The control module monitors how long it take the sensor to warm up and start sending an adequate signal. The code is triggered when the sensor is taking too long to warm up. Water getting inside the heated oxygen sensor connector can caused the heated oxygen sensor fuse to blow. Before replacing the sensor, check for the condition of the heated oxygen sensor fuse and connectors. If the sensor and connector are OK, replacing the O2 Sensor 1 usually takes care of the problem... Current amperage in the rear heated oxygen sensor heater circuit is out of the normal range. Possible symptoms - Engine Light ON (or Service Engine Soon Warning Light) - Possible higher than usual fuel Consumption P0141 Toyota Description.... Oxygen Sensors (O2S) or Heated Oxygen Sensors (HO2S) need to reach a minimum operating temperature of 750 degrees F to produce an accurate voltage signal. The faster the heated oxygen sensor reaches that temperature the faster the sensor will start sending an accurate signal to the Engine Control Module (ECM). In order to achieve the require temperature, a heater element is included inside the heated oxygen sensor. The ECM controls the heated oxygen sensor heater element based on signals from the engine coolant temperature and engine load. The ECM controls the heater element circuit by allowing current flow to ground. The ECM monitors the voltage signal received through the heater element circuit and determines the state of the circuit by comparing the voltage detected with the factory specifications.

Thank you very for your valuable information. I just had the oxygen sensor replaced for total amount of $448 at the dealer. I was advised I need to drive for 70 to 80 miles before I send back for smog retest. Do you think it is necessary? Very much appreciated of your valuable and responsive advice. Thank you very much!

Actually you need to drive the car when the gas tank is 3/4 full down to 1/4 tank of gas. Thats when the computer will do a diagnostic test on all the system of the car. So you don't add gas until you get down to 1/4 tank. But the code or codes would have to be reset (check engine light off) before doing this. So if the check engine light comes back on during this time, then there is still a problem.

Thanks again for your advice. Keep my fingers crossed :)

Your welcome.