Diagnostic Aids

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.

After confirming DTC P1130 and/or P1150, use scan tool to access CURRENT DATA to confirm voltage output of A/F sensors (banks No. 1 and 2, sensor No. 1).ECM controls voltage of AFR+, AFL+, AFR- and AFL- terminals at ECM to a fixed voltage (3.3 volts at AFR+ or AFL+ terminal; 3.0 volts at AFR- or AFL- terminal). It is impossible to confirm A/F sensor output voltage without using a scan tool. OBD-II scan tools will display one fifth of A/F sensor output voltage that Lexus scan tool will. Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.

During fuel enrichment, output voltage of A/F sensors may be less than 0.56 volts (2.8 volts on Lexus scan tool). During fuel cut, output voltage of A/F sensors may be more than 0.76 volts (3.8 volts on Lexus scan tool). If output voltage of A/F sensor remains at 0.66 volts (3.3 volts on Lexus scan tool) during all conditions, A/F sensor circuit may be open. If output voltage of A/F sensor remains at 0.76 volts (3.8 volts on Lexus scan tool) or more during all conditions, A/F sensor circuit may be shorted. If output voltage of A/F sensor remains at 0.56 volts (2.8 volts on Lexus scan tool) or less during all conditions, A/F sensor circuit may be shorted.