Circuit Description

WARNING: This page is about a different car, the 2002 Lexus RX 300. However, it is still accessible from the selected car via links, so may be relevant.

Air/Fuel (A/F) sensor monitors exhaust gas oxygen content and delivers an input signal to ECM. ECM uses input signal to control air/fuel ratio. A/F sensor includes a heater. DTC is set when A/F sensor output signal deteriorates with engine speed at 1400 RPM or more, and with vehicle speed at more than 38 MPH. DTC P1133 is for bank No. 1 A/F sensor. DTC P1153 is for bank No. 2 A/F sensor. Possible causes are:

Open or short in A/F sensor circuit.
Faulty A/F sensor.
Air induction system malfunction.
Improper fuel pressure.
Faulty fuel injector.
Faulty ECM.