Question

2000 Lexus GS300 with codes P0135 and P0141, what do these codes represent?

Answer 1

Both of these codes refer to the heater on the front O2 sensors. It isn't specific to bank one or bank 2. So, you need to check for power to the sensor heater wire,thenif there is power, check the resistence of the heater on the sensor. If you locate one with no resistance, the sensor is no good and will need to be replaced to resolve the code.

Answer 2

P0135 LEXUS - Heated Oxygen Sensor Heater Circuit Malfunction Bank 1 Sensor 1
Read more: https://www.autocodes.com/p0135_lexus.html

P0141 LEXUS - HO2S12 Heater Circuit Malfunction
Read more: https://www.autocodes.com/p0141_lexus.html