The oxygen sensor of Jetta is broken. Does it affect the car?

As an important part of electronically controlled fuel injection system, oxygen sensor plays a vital role in the normal operation of the engine and the effective control of exhaust emissions. Once the oxygen sensor and its connecting circuit fail, it will not only make the emission exceed the standard, but also worsen the engine working condition, leading to the symptoms of idling, inaccurate engine operation, power decline and so on.

There are usually two oxygen sensors, the front oxygen sensor is located in the exhaust manifold and the rear oxygen sensor is located behind the three-way catalyst. Pre-oxygen is used to adjust the concentration of mixed gas, and post-oxygen is used to monitor the working condition of three-way catalyst.

The influence of the front oxygen fault on the car is that the mixture can not be corrected, which will increase fuel consumption and reduce the power of the car. Then the oxygen fault means that it is impossible to judge the working condition of the three-way catalyst. Once the three-way catalytic converter fails, it cannot be repaired in time, which will eventually affect the working condition of the engine.

Extended data

The core components of oxygen sensor are porous ZrO2 ceramic tube, solid electrolyte and porous platinum (Pt) electrode sintered on both sides.

At a certain temperature, due to the different oxygen concentrations on both sides, oxygen molecules on the high-concentration side (inside the ceramic tube 4) are adsorbed on the platinum electrode, and combine with electrons (4e) to form oxygen ions O2-, which makes the electrode positively charged, and O2- ions migrate to the low-oxygen concentration side (exhaust gas side) through oxygen ion vacancies in the electrolyte, which makes the electrode negatively charged, that is, a potential difference is generated.

When the air-fuel ratio is low (the mixture is rich), there is less oxygen in the exhaust gas, so there are fewer oxygen ions outside the ceramic tube, forming an electromotive force of about 1.0V;

When the air-fuel ratio is equal to 14.7, the electromotive force generated on the inside and outside of the ceramic tube is 0.4V~0.5V, which is the reference electromotive force;

When the air-fuel ratio is high (lean mixture), the oxygen content in the exhaust gas is high, and the difference of oxygen ion concentration inside and outside the ceramic tube is small, so the electromotive force is very low and close to zero.

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