O2 sensor

Asked by Feb 04, 2013 at 02:01 PM about the Volkswagen Jetta

Question type: Maintenance & Repair

We know that it measures the amount of oxygen, we just don't know which pnp npn functions this information will help? also, from my good friend Gary:What's an o2 sensor? and did you know that there are valuable metal in a catalytic converter and people steal them? ....like who 's gonna buy some nasty exhaust covered rare metal?  Take it to the jewelers?

7 Answers

James Ramond

ahh. hello, why do you think platinum exceeded gold for the past 10 yrs on the metals market, it sure aint prettyier .and function is to aquire stichieo or whatever they call a perfect mix ratio like 14 to one air fuel for slow burn, that may have even changed by now with the crap they sell at the pumps these days, and the two sensors on the cat fr. and rear each have their own function

1 out of 1 people think this is helpful.

Scrap yards and eBayer's buy used catalytic converters. I do know that people steal them. I had one stolen from me.

1 out of 1 people think this is helpful.
Lars Cats

Lambda sensors, colloquially known as O2 sensors, make modern electronic fuel injection and emission control possible. They help determine, in real time, if the air–fuel ratio of a combustion engine is rich or lean. Since oxygen sensors are located in the exhaust stream, they do not directly measure the air or the fuel entering the engine. But when information from oxygen sensors is coupled with information from other sources, it can be used to indirectly determine the air-fuel ratio. Closed loop feedback-controlled fuel injection varies the fuel injector output according to real-time sensor data rather than operating with a predetermined (open-loop) fuel map, improving fuel consumption and lowering potentially harmful emissions.

7 out of 7 people think this is helpful.
Best Answer
Scott Sr.

And...the O2 sensor is also a bimetallic device with platinum which changes its voltage in the lambda circuit in relation to the ratio of oxygen in the exhaust stream relative to ambient oxygen levels. They have a limited life-span and must be replaced at regular intervals.

2 out of 2 people think this is helpful.

I will take Lars answer one step further,the O2 sensors job is very important to modern engine controls.The make up of the sensor consists of a zircon element,it was discovered many years ago that this element will produce a minute electrical current in the presence of oxygen,in the modern automobile this current is used by the engines management computer to vary the injectors cycle time to keep the mixture as close to "lambda" or the ideal mixture ratio of 14.7 to 1 that is the ideal fuel to air ratio for absolute complete combustion,using a mass air flow sensor ,or a Map sensor to determine engine loads,all of the components work together to keep the mixture at that ideal.When one or more of these components gets out pf sync .more than three times a trouble code is generated and the check engine lamp is triggered on. The catalytic converter uses the oxygen in the exhaust stream in combination with the platinum and other exotic elements in the ceramic element to convet the harmful gases into harmless co2 and water vapor,as any thing automotive it has a finite life,the rear O2 sensors job is to send a reading to the engines computer.where it is compared to the front sensor,too slow a response or if it is working almost the same as the front sensor is an indication that the converter is starting to lose it's efficiency,in an ideal world all work together to produce clean air from bad.Any variations will set the light,indicating service is required.

5 out of 5 people think this is helpful.
Scott Sr.


3 out of 3 people think this is helpful.

Best bet is to go OE on sensors Bosch or Hitachi for Asian systems,and always get the correct ends,these universal sensors they sell ,unless they are installed absolutely the correct way.You will encounter problems,the voltages are so small that any interference by a poor electrical connection will create issues.

2 out of 2 people think this is helpful.

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