Rear O2 Sensor Simulators are used in off road/racing vehicles to prevent the check engine light from illuminating and to prevent an ECU code from tripping (P-0420 and/or P-0430) when the catalytic converter(s) are removed for off road/racing use. URD Rear O2 Sensor Simulators are carefully calibrated to condition the signal from the rear O2 sensor to keep it in the range the ECU is expecting to see. DO NOT USE ON A PUBLIC ROAD OR HIGHWAY ANYWHERE IN THE UNITED STATES.
Note: Be cautious of O2 sims that replace the rear O2 sensor with a falsely gererated signal.
Toyota started using a wideband type O2 sensor (air/fuel ratio) in the front position for better engine control. These wideband type sensors need to be recalibrated from time to time by the ECU. The ECU uses the rear sensors for this recalibration process. The ECU cannot properly recalibrate the wideband sensor using a falsely generated signal. This process is explained here, US Patent 5706654.
Use only a URD O2 Sensor Simulator on these vehicles to avoid poor performance, drivability issues and poor MPG.
Most of our customers are using their vehicles for dual use. During the week they use them for commuting and on the weekends use them for off road use and sanctioned racing events. Most of the URD Rear O2 Sensor Simulators can be very quickly plugged in for your off road events and then quickly removed for on highway use.
Single Channel units- Locate the rear O2 sensor. This will be to the rear of the catalytic converter. Follow the wire from that sensor until you locate the harness connector. Unplug the connector and plug one plug from the unit into the O2 sensor and the other to the harness connector and tie the unit to the harness away from the exhaust.
Dual Channel Units- Locate the rear O2 sensor on the passenger side of the vehicle. This will be to the rear of the catalytic converter. Follow the wire from that sensor until you locate the harness connector. Unplug the connector and plug one plug from the short harness into the O2 sensor and the other to the harness connector. Pass the long harness over the transmission and do the same on the driver's side. Secure the control unit to the connector bracket on the side of the transmission with a wire tie.
For the wired in units follow the wiring guide included with your simulator.
Note- The URD Rear Sensor Simulator cannot be used to replace or fix a rear O2 sensor that is not working correctly. If you have a failed rear O2 sensor you will need to replace that rear O2 sensor with a properly functioning one. The URD Rear O2 Sensor Simulator is designed to modify and condition the signal from a properly working rear sensor. If you need a replacement O2 sensor you can find them here on the URD Site. URD O2 Sensor Page.
Sensor Simulators are not CARB Approved, and are never to be used on Pollution Controlled Vehicles or on Public Highways