Increased fuel consumption, jerks when accelerating rapidly, increased toxicity - all these problems can be caused by a malfunction of a small device called a lambda probe or oxygen sensor.
Oxygen sensor
Its function is to regulate the ratio of air, fuel in the combustion chambers. If the mixture is too lean or, on the contrary, too rich, the sensor will send a signal to the control unit and he will correct the situation. The manufacturer can equip its vehicles with several types of lambda probes. The device can be one-, two-, three and even four-wire. In any case, one of the wires is a signal one (usually it is black), the others are for the heater (usually they are white). On a car where an oxygen sensor was installed without a heater, you can put any lambda probe with a heater (you need to connect the "extra" wires through a relay), but you can't do the opposite.
The failure of the oxygen sensor can be caused by several reasons, among which the most common is the use of low-quality or unrefined gasoline, which can be caused by improper operation of the fuel pressure regulator, contamination of the gasoline filter. Other reasons include:
- hitting the sensor body of a coolant (or brake) fluid;
- cleaning the lambda probe housing with means that are not intended for this.
Checking the sensor with a tester
First, visually inspect the sensor. If it has a lot of soot, lead, or light gray deposits, it is best to replace it. If the lambda probe is relatively clean, then further tests can be carried out (an assistant will be needed). Start up the engine, warm it up to a temperature of 70-80C. Find the signal wire on the sensor and ask the assistant to raise the crankshaft speed to 2500-3000. Keep this operating mode for 3 minutes to warm up the sensor.
Now measure the voltage on the signal wire (connect the negative probe of the tester to the car ground), - it should be in the range from 0.2 to 1V and not constant, but turn on and off with an approximate frequency of 8-10 times per second. When the accelerator pedal is pressed sharply, a serviceable sensor will show a voltage of 1V; when the pedal is released abruptly, it will drop to almost zero. If the voltage on the signal wire does not change and is approximately 0.4-0.5V, then the sensor must be changed. In the complete absence of voltage, it is necessary to make sure that the wiring is in good condition; "Ring" the tester wires suitable for the ignition switch or relay. Also check the connection of the mass to the lambda probe heater.
