Dummy load for secondary O2 sensor

[kebbz]

For those who took out their catalytic converters here is a dummy load to replace the secondary O2 sensor and fool ECU that the converter is working properly by supplying around 0.5 volts to ECU.

The idea is simple to make 0.5 volts from 12v supply with simple voltage divider. 1k resistor is there to fool ECU that heater circuit is working properly, the red wire from the 470 Ohm resistor goes to vehicle ground (chasis).

I just took a connector from the old sensor and soldered the resistors to the wires that went to the sensor. The result is shown on the graph. For finetuning the desired voltage you can change the 10k Ohm resistor.

 

[fingers99]

I have it on good authority that just wrapping the post cat sensor in aluminium foil does the job just fine.

OK, so yours is a neater solution.

 

[kebbz]

Sorry guys, but this previous build gives the check engine light and a O2 heater error so here is the working version.
The thing is that the resistor between two white wires (heater) has to be from 12 to 60 Ohms and at least 20 watts and it will get very hot during operation. Here is the fix: just return the sensor and connect back only the heater (white wires) and leave the sensor black and gray wires disconnected, keeping the voltage divider circuit. The result is almost factory like setup except that additional wire for ground reference. The resistors are under the rubber cable shield, and you can connect the ground reference wire (in this case red) under any screw that has connection with chasis.