In the use of three-way catalytic converter to reduce the exhaust pollution of the engine, the oxygen sensor is essential components. Since the air-fuel ratio of the mixed gas deviates from the theoretical air-fuel ratio, the purifying capacity of the three-way catalyst to CO, HC and NOX will drop sharply. Therefore, an oxygen sensor is installed in the exhaust pipe to detect the oxygen concentration in the exhaust gas, ECU sends a feedback signal, and then by the ECU control fuel injector fuel injection volume increase and decrease, so that the air-fuel ratio of mixed gas control in the vicinity of the theoretical value.
At present, the actual application of oxygen sensors are zirconia oxygen sensor and titanium oxide oxygen sensor two. And the common oxygen sensor and a single lead, double lead and three lead points, single lead for the zirconia oxygen sensor; double lead for the titanium oxide oxygen sensor; three lead for the heating type zirconia oxygen sensor, In principle, three kinds of lead wire oxygen sensor can not be used instead.
Once the oxygen sensor failure, will make the electronic fuel injection system of the computer can not get the oxygen concentration of the exhaust pipe information, and therefore can not feedback control of the air-fuel ratio, the engine fuel consumption and exhaust pollution will increase, the engine idle instability, Lack of fire, surge and other symptoms. Therefore, the failure or replacement must be eliminated in a timely manner.
Oxygen sensor common faults
1, oxygen sensor poisoning
Oxygen sensor poisoning is often a difficult and difficult to prevent and control a failure, especially in the often use of leaded gasoline cars, even the new oxygen sensor, can only work thousands of kilometers. If only a slight lead poisoning, then use a box of lead-free gasoline, you can eliminate the oxygen sensor surface lead, to return to normal work. But often due to the high exhaust temperature, leaving the lead into its internal, hinder the proliferation of oxygen ions, so that oxygen sensor failure, then only can be replaced.
In addition, oxygen sensor silicon poisoning is also common. In general, the silicon dioxide and silicone rubber gaskets produced by the combustion of silicon compounds contained in gasoline and lubricants use improperly emitting silicone gases that will render the oxygen sensor ineffective, thus using good quality fuel and lubricants The Repair and use the right to choose and install the rubber gasket, do not apply to the sensor factory use of solvents and anti-adhesion agent.
2, carbon deposition
Due to the engine combustion is not good, in the oxygen sensor surface formation of carbon deposition, or oxygen sensor into the internal oil or dust and other deposits, will hinder or block the outside air into the oxygen sensor inside the oxygen sensor output signal inaccurate, ECU can not be timely To correct air-fuel ratio. Resulting in carbon deposition, mainly for the fuel consumption increased, significantly increased the concentration of emissions. At this point, if the sediment is cleared, it will return to normal work.
3, oxygen sensor ceramic fragmentation
Oxygen sensor ceramic hard and brittle, with a hard object percussion or purge with a strong airflow, are likely to break it and fail. Therefore, the treatment should be particularly careful to find the problem in time to replace.
4, the heater resistance wire blown
For the heating type oxygen sensor, if the heater resistance wire ablation, it is difficult to make the sensor to the normal working temperature and lose its role.
5. Oxygen sensor internal line off.