Pre-catalytic converter oxygen sensor

What we will cover in this article is how to by-pass the O2 sensor. The one that might need to bypass is the one after the catalytic converter. We will cover a couple of different methods and explain the pros and cons to each one, and we will also explain why you might want to bypass the oxygen sensor. Before going into the different methods, we will briefly cover why you might want to bypass the O2 sensor.

Your vehicle may not have the catalytic converter for a variety of reasons. It might have fallen off, got a hole in it, or been removed for more horsepower, but without it, your car will always have a check engine light if you still have a functioning O2 sensor. This can be annoying and also lead to other problems happening that is why it is important to try to get it to turn off by bypassing the O2 sensor. A functioning oxygen sensor leads right into our first way around it, and that is to put a dummy O2 sensor in.

A dummy O2 sensor is a fake one that does readings like a normal one. A dummy one sends the cars computer the proper information that a normal one would send if it were reading correctly. Dummy O2 sensors are easy to use. All you have to do is locate your cars current O2 sensor and unplug it.

You then plug the new one in. It is that simple or is it? Well, with dummy O2 sensors sometimes the cars computer can tell that it is a fact sensor and this will cause your car not to run right.

That is why if you want to go with a dummy sensor you will need to make sure that you get one that is programmed to work with the vehicle you have. Also, buying dummy O2 sensors can be a challenge because removing your catalytic converter is illegal and the only reason why you would need a dummy O2 sensor is if you had done that.

Another name for dummy O2 sensors is O2 Simulators. An oxygen sensor simulator will send the computer the proper wavelengths. They work with resistors and capacitors. Gasoline and diesel fuel are refined products from crude oil that contain a mixture of different hydrocarbons including olefins, benzene and the chemical element sulfur. Sulfur is a chemical element that occurs naturally in crude oil. The refining process reduces the concentration of sulfur in the gasoline.

Sulfur can cause the degradation of an oxygen sensor and the concentration of the sulfur in the gasoline will determine the rate at which the sensor will degrade. Gasoline with a sulfur content of 1, parts per million ppm has been shown to cause accelerated degradation, resulting in the illumination of a service soon light. To put 1, ppm in perspective, if you have a thousand gallons of gasoline, it will have one gallon of sulfur. Gasoline also contains other added ingredients.

The following are gasoline additives: octane enhancers, antioxidants, metal deactivators, ignition controllers, icing inhibitors, detergents and corrosion inhibitors.

One of these ingredients is MBTE methyl tertiary-butyl ether. It was originally introduced in the late s as an octane enhancer to replace tetra ethyl lead for catalytic converter-equipped vehicles. It is also used as an oxygenate.

MBTE has little or no effect on the operation of the oxygen sensor introduced in the s. This has affected the life of some newer oxygen sensors. Advertisement Alcohol in the form of methanol and ethanol are oxygenates that are added to gasoline. E85 will burn cleaner and produce less degradation of the oxygen sensor. But, it is a compromise in fuel economy, because there is less energy in a gallon of E85 than a gallon of gasoline. Methanol is a fuel associated with racing.

It is a hazardous material and poisonous, which limits its use as a commercial fuel. Motor oil contains phosphorous, which can also cause the degradation of the sensor when excessive oil vapor is introduced through crankcase ventilation.

So one of the components that should be recommended after an oxygen sensor replacement is the PCV valve. Oxygen Sensor Failure The most vulnerable part is the wiring and connector, followed by the heater. Its function is to bring the sensor to operating temperature during cold starts and engine warm up. It can be damaged by thermal shock.

Advertisement Excessive heat is usually the cause for damage to the wiring. If the connector and wiring is not properly routed and secured, there is a good possibility that either or both can be damaged.

The Role of Engine Maintenance Does overall engine maintenance affect the life of an oxygen sensor? Simple answer: Yes. An important maintenance item is the oil change. It contributes to the life of an oxygen sensor. Positive crankcase ventilation PCV can contribute to the degradation of the oxygen sensor. If there are no O2 sensor codes and both sensors are functioning normally, you should see a lot of switching activity in the upstream O2 sensor s and very little switching activity in the downstream O2 sensor s if the converter is good.

If the downstream O2 sensor activity mirrors the upstream O2 sensor, the converter is dead and needs to be replaced. On V6 and V8 applications with dual cat exhausts, you'll have upstream O2 sensor readings for each side of the engine and downstream O2 sensor readings for each converter. Check and compare both sides. Most scan tools can access a menu called "Mode The Mode 06 menu lists self-test data for all the non-continuous monitors, including the catalyst monitor.

The nice thing about the Mode 06 data is that it will show you if the catalyst or oxygen sensor heaters are operating within normal limits. A problem may not have set a DTC yet, but if it is misbehaving you can see it in Mode See the Mode 6 section for more information on how to use Mode 06 diagnostics. On and newer vehicles, the federal emissions warranty on the converter is 8 years or 80, miles. There are strict rules that apply to replacing converters that are still under warranty.

Even so, OEM converters can be replaced with aftermarket converters even when vehicles are still under warranty but at the customer's expense for any of the following reasons which must be documented :. A replacement converter must be the same type as the original two-way, three-way or three-way plus oxygen , EPA certified and certified as being OBD II compliant.

You may run into a situation where the catalyst monitor won't run because there's an O2 sensor code. The OBD II system can't evaluate the converter if the upstream and downstream O2 sensors are not functioning normally.

O2 sensors typically fail because of old age or contamination. Older generation O2 sensors may become sluggish once they've seen 50, miles of service. Newer generation O2 sensors should last , miles or more, but may also become sluggish if contaminants from the engine have fouled the sensor. Silicone from internal coolant leaks and phosphorus from burning oil are the two main contaminants that can kill an O2 sensor.

If an engine has suffered a recent head gasket failure, the O2 sensors may need to be replaced because of contamination. A good O2 sensor should show a lot of switching activity with readings bouncing back and forth from 0. If the sensor is sluggish or reads low, it needs to be replaced.

Home Contact Support Knowledgebase. Knowledgebase: General. Even so, OEM converters can be replaced with aftermarket converters even when vehicles are still under warranty but at the customer's expense for any of the following reasons which must be documented : The vehicle failed an emissions test.

The original converter is damaged clogged or rusted , or missing.