Circuit Description

WARNING: This page is about a different car, the 2003 Lexus GX 470. However, it is still accessible from the selected car via links, so may be relevant.

For circuit description, see CIRCUIT DESCRIPTION under DTC P0031, P0032, P0037, P0038, P0051, P0052, P0057 Or P0058. DTC is set when speed changes of more than 3 MPH occur more than 30 times (as detected by ECM), and there is no change in rich and lean outputs from heated oxygen sensor for 480 seconds of air fuel ratio feedback (throttle was not closed). Possible causes are:

Open or short in heated oxygen sensor circuit.
Defective heated oxygen sensor No. 2.
Defective heated oxygen sensor heater No. 2.
Defective EFI relay.