Last Updated: 05/26/2022 @ 07:19 am

This is another option for buying O2 Simulator. They have been testing and fully working on 2002-2003 5thgen Maximas. Should also work on 2004-2008 6thgen Maximas as well.

Price: $199.98

The iO2 was originally developed as tool to aid in the diagnosis of catalytic converter and oxygen sensor fault codes.We believe this is the most intelligent oxygen sensor simulator available, that’s why we named it the iO2. The iO2 uses the vehicles live oxygen sensor signal to emulate and output a signal that closely resembles that of  a good  functioning catalyst.

The desire to simulate an o2 sensor begins with the desire to remove the catalytic converters to allow free’er exhaust flow. The trouble is, the rear o2 monitors the exhaust content and the PCM can determine if the catalyst if performing or not. If the catalyst is removed, the PCM usually starts reporting P0420,p0430 faults for catalyst efficiency.

Simulation approaches in our research showed two basic idea’s, an electronic and a exhaust spacer approach (defoulers)

Electronic Simulators 


Let’s start with electronic, the 555 timer. Developed years ago the 555 timer was and still is the electronics hobbyist dream.The 555 timer was setup in such a fashion to simply output 450 mv to keep the PCM thinking the rear o2 was present.
However as PCM’s grew in software function, tests were added to check if the rear o2 was actually able to produce a voltage range of 0-1 volt.Of course, this made the original 555 design obsolete, so the output of the 555 was changed to pulse from 0-1 volt at a fixed or even adjustable rate, this is the most current use of the 555 that we know of.
This does work for older technology, however it is hit or miss or will not work for newer PCM’s. It is a unreliable approach that will more than likely lead to an catalyst efficiency fault at some point.


The resistor capacitor fix….cap

An very common electronic filter circuit, but does it work?
About as well as the 555, yes and no, its once again hit or miss dependent on the vehicle. It will pass the PCM’s test for o2 sensor activity, just like the 555 timer will, but when it comes time to test for catalyst efficiency (p0420,p0430) that’s when they fall short.



The direct approach, this seems to be very popular maybe      because electronic approaches haven’t been very reliable, and its  cheap. Do they work? once again yes, and no. First they are far  from from stealthy, secondly they require routine maintenance.

They are not a guarantee for every vehicle, difficult to get just right  and require cleaning from time to time

At any rate, we just wanted to provide some insight based on our research.

The io2 IS different.

The io2 itself, is actually a programmed device that reads an actual o2 sensor voltage, then cleans it up.
The software within the io2 will force the output to act as though a catalytic converter is present in the exhaust. So the PCM will see the signal, pass the o2 function test and when it comes time for the dreaded p0420,p0430 the software takes care of that too.

scantool2The io2 during testing. The io2 was installed on a 2007 Chrysler product to field test the software. This test vehicle was driven in excess of 850 km’s in all driving conditions, with no P0420 or catalyst efficiency codes generated.
the io2 was installed on bank1, input was taken from the bank1 primary O2, the rear o2 sense wire was cut and spliced to the io2 output.


Question and Answers

Question; What about some other devices on the market for simulating o2 sensors?

Answer; Many devices currently on the market are based on a 555 timer, or a simple low pass filter circuit. Yes they do work, sometimes, sometimes they don’t, they are hit or miss. The iO2 is a programmed microcontroller with software that creates the simulated output voltage, we feel the most reliable approach.

Question; How many iO2’s will I need? some devices can be wired to two o2 sensors at the same time.

Answer; you will need as many io2’s as you have rear oxygen sensors (please see our support page). You cannot reliably  use a single simulator for two rear o2 sensors, eventually the engine computer on many vehicles will try to test the function of the rear o2 sensors, it may not test each one at the same time, unlike other simulators,the io2’s software is designed to recognize these tests,so simply put, this will not and cannot work.

Question; Will the iO2 work on my “whatever” vehicle?

Answer, YES! as long as you are using a low band O2 sensor as the input (every vehicle uses a low band for the rear O2 sensor) and the output is simulating a low band O2. This includes all vehicles, even Chrysler,Jeep and Dodge products.


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