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 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 amp. Possible causes are:

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