Many vehicle owners struggle with passing the emissions test. Even more of them opt for installing O2 sensor spacers.
However, did you know that O2 sensor spaces are illegal in many states?
Well, I learned the hard way.
If you do not want to end up with a big fine, read on to find out more about O2 sensor spacers and why are they illegal.
What Are O2 Sensor Spacers?
O2 sensor spaces also referred to as O2 extenders, O2 emulators, and O2 adapters are small metal tubes that are installed on the O2 sensor head and then into the exhaust system.
The O2 sensor spacers are used to remove the O2 sensor from the direct path of the exhaust gases coming from the catalytic converter.
This means that the O2 sensor is still present but it is not in the direct path and will not measure all of the exhaust gasses going into the catalytic converter.
They are often used when a vehicle is unable to pass an emissions test due to a bad catalytic converter.
When the catalytic converter is clogged or simply faulty, it is not able to reduce the harmful elements from the exhaust gasses before releasing them into the atmosphere.
The increase of harmful exhaust gases will be picked up by the O2 sensor and a check engine light will be triggered.
However, if you install an O2 sensor spacer, especially one with a catalytic converter built-in, the readings of the harmful exhaust gasses will be significantly lower, tricking the ECU that everything is working fine.
Even with the O2 sensor being pulled out, exhaust gasses will still go into the sensor. But the volume of exhaust gasses that will actually reach the O2 sensor is very small and will trick the ECU that everything is alright.
How Do 02 Sensor Spacers Work?
The O2 sensor spacers are installed on the oxygen sensor and it tricks the vehicle’s computer into thinking that the catalytic converter is working and it keeps the check engine light off.
These spacers are pretty much tubes that pull away the head of the O2 sensor from the exhaust gas flow direction.
By removing the O2 sensor from the direct flow of exhaust gasses with the help of the spacers, the ECU is tricked because the O2 sensor will not measure all of the exhaust gasses and will not report that the catalytic converter is not working properly.
There are two types of O2 sensor spacers including the ones with a miniature catalytic converter filter, and the ones without.
The O2 sensor spaces that have a mini catalytic converter filter with a catalyst are better at deceiving the ECU to think that your vehicle has a working catalytic converter.
O2 sensor spaces are not going to work for vehicles that have the P0430 trouble code because that means you have an unmetered air leak which is going to trigger the P0420 trouble code as well.
However, if your vehicle has a P0420 which means that the catalytic converter is pretty much burnt out, installing an O2 sensor spacer will trick the vehicle’s computer to think that everything is alright and not trigger any codes.
Are O2 Sensor Spacers Illegal?
Yes. O2 Sensor spaces are illegal in all states (a total of 34 states) that require vehicles to pass an emissions test.
O2 sensor spaces are illegal because they provide a faulty emission reading by pulling away the O2 sensor from the direct path of the exhaust gases and it is unable to measure correctly.
In a normally operating car, the catalytic converter should remove harmful pollutants from the exhaust gases before releasing them into the atmosphere.
However, if the catalytic converter is faulty, those exhaust gasses will be released as they are straight from the combustion chamber.
This will get picked up by the O2 sensor and a check engine light will be triggered, suggesting a faulty catalytic converter.
By installing an O2 sensor spacer, you are actually reducing the volume of unfiltered exhaust gases going into the O2 sensor, thus tricking the vehicle’s computer that the catalytic converter has done its job and no check engine light will be triggered.
This being said, if you live in a state that has an emissions test, do not even bother installing O2 sensor spaces because the technicians will see it and your vehicle will not pass the emissions test.
Where Are O2 Sensor Spaces Illegal?
| State | Has Emissions Test | O2 Sensor Spacers Illegal |
|---|---|---|
| Alaska | Yes | Yes |
| Arizona | Yes | Yes |
| California | Yes | Yes |
| Colorado | Yes | Yes |
| Connecticut | Yes | Yes |
| Delaware | Yes | Yes |
| District of Columbia | Yes | Yes |
| Georgia | Yes | Yes |
| Idaho | Yes | Yes |
| Illinois | Yes | Yes |
| Indiana | Yes | Yes |
| Kentucky | Yes | Yes |
| Louisiana | Yes | Yes |
| Maine | Yes | Yes |
| Maryland | Yes | Yes |
| Massachusetts | Yes | Yes |
| Missouri | Yes | Yes |
| Nevada | Yes | Yes |
| New Hampshire | Yes | Yes |
| New Jersey | Yes | Yes |
| New Mexico | Yes | Yes |
| New York | Yes | Yes |
| North Carolina | Yes | Yes |
| Ohio | Yes | Yes |
| Oregon | Yes | Yes |
| Pennsylvania | Yes | Yes |
| Rhode Island | Yes | Yes |
| Tennessee | Yes | Yes |
| Texas | Yes | Yes |
| Utah | Yes | Yes |
| Vermont | Yes | Yes |
| Virginia | Yes | Yes |
| Washington | Yes | Yes |
| Wisconsin | Yes | Yes |
Is It Bad To Drive Without An Oxygen Sensor?
Yes, it is bad to drive without an oxygen sensor. An oxygen sensor monitors the amount of oxygen in your car’s exhaust gas and helps regulate engine performance by adjusting the fuel-air ratio. Without the oxygen sensor, your car’s engine can run rich or lean, causing poor fuel economy and increased emissions.
On top of that, it is illegal in most states to drive without an oxygen sensor. If your oxygen sensor is bad, you should first try to clean it.
If the cleaning doesn’t work, you should replace the faulty oxygen sensor.
Related articles:
- P0442 OBD-II Evaporative Emission System Leak Detected (small leak) Trouble Code
- P0443 OBD-II Evaporative Emission System Purge Control Valve Circuit Trouble Code
- P0455 OBD-II Evaporative Emission System Leak Detected (Large Leak) Trouble Code
- P0456 OBD-II Evaporative Emissions System Small Leak Detected Trouble Code
- P0430 OBD-II Catalyst System Efficiency Below Threshold Bank 2 Trouble Code
- How to Get Your Car to Pass the Emissions Test
In Conclusion
O2 sensor spacers are illegal in most states and should not be installed if your state requires an emissions test.
Instead, you should try and figure out if your catalytic converter is only clogged and needs cleaning, or if it has completely failed and needs replacing.