Circuit Description

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 applies to bank No. 1 sensor No. 1 and DTC P1155 applies to bank No. 2 sensor No. 1. Heated A/F sensors are located on exhaust manifold above catalytic converters. A/F sensor for cylinders No. 1 and 4 is referred to as bank No. 1 sensor No. 1. A/F sensor for cylinders No. 2 and 3 is referred to as bank No. 2 sensor No. 1. A/F sensors may also be referred to as A/F ratio sensors. DTC is set when A/F sensor heater output is more than 10 amps or when heater output is less than .8 amp. Possible causes are:

• A/F sensor heater circuit is open or shorted.
• Defective A/F sensor heater.
• Defective ECM.