Simplest Narrowband OX sensor simulator

BUILDING IT

 Hi, today I'll be sharing with you how to build a very simple narrowband oxygen sensor simulator, this thing is only useful to troubleshoot how an ECU reads the 2 states of an oxygen sensor. it does not simulate an oxygen sensor heater. On your left you will see the sensor curve for all NB oxygen sensors. the tool is simply a switch that outputs a ground path, or about 0.75 to 1V. allowing the user to simulate a rich or lean reading.




The Parts needed are very simple, and should be found at all local electronic parts shop.

4 X 1K resitors. 1/4w is fine
2 x 10k resistors. 1/4w is fine
3 x wires of different colors ,about 2 feet long gauge 20
1 x single pole double throw switch, something with 3 pins
2 x shrink wrap tubing for protecting the circuitry , or electrical tape

optional parts
shrink wrap to hide all of the 3 wires and the circuitry
3 x crocodile connectors

 Here you can see how I built it. very simple to do, twisting the resistors together and soldering it all in the end. adding the wires.

 complete tool ready for use

AND NOW PLAYING WITH IT

 I went ahead and proved the tool on my own like all mad scientist should be doing. Test subject is a 1997 toyota corolla, AE102 at birth , converted with an 92-93 3VZ-FE running a Canadian OBD1 A/T ECU with an OBD1READ device used in conjunction with TOYOBD1.

the tool sits on the front engine bank with the orange wire connected at the alternator pole, and the green wire connected to the chassis ground. white wire leads to the front bank ox sensor wire

 

First I warmed the engine up. then when ready ,toggling the switch with one hand an data logging in toyobd1 with the other I was able to fool my ECU into thinking the sensor reading was either rich or lean.

Summary

This tool can be used to make sure the wiring and  ECU are correctly working. leaving the only possible culprit to the sensor itself if something is wrong.