2000 lexus gs 300

First thing to do would be to extract the codes with a scan tool. Once you have the codes you can post them below and we will guide you further.

If I had to guess, I would be thinking vacuum leak.

The codes indicate multiple misfires and O2 sensor failure. I would check/Replace the Faulty O2 Sensor, clear the codes and test it again.

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P0135 Toyota – Heated Oxygen Sensor Heater Circuit Malfunction Bank 1 Sensor 1

Possible causes
– Faulty Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1
– Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1 circuit fuse
– Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1 circuit open shorted to ground
– Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1 circuit poor electrical connection
– Faulty Engine Control Module (ECM)

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.

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)

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 .

It was a guess. Since you were able to post the codes we were able to Know instead of guess.

“The codes indicate multiple misfires and O2 sensor failure. I would check/Replace the Faulty O2 Sensor, clear the codes and test it again.”