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 P1135 is for bank No. 1 A/F sensor. DTC P1155 is for bank No. 2 A/F sensor. DTC is set when A/F sensor heater output is more than 8 amps or when heater output is less than .25 amps. Possible causes are:

Open or short in A/F sensor heater circuit.
Faulty A/F sensor heater.
Faulty ECM.