Device and repair of Toyota RAV4 SUVs (Toyota RAV) - Replacement of sensors of oxygen (O2S) and fuel-air mix (A/F Sensor)-//

Toyota PAB4-Toyota RAV4
1. Operation of the car
2. Maintenance
3. Engines
4. Cooling systems and conditioning
5. Fuel system and system of production of the fulfilled gases
6. System of ignition
7. The control system and decrease in toxicity of the fulfilled gases
   General information
   Technical characteristics
   System of onboard Diagnostics (OBD)
   Information sensors and executive stroystvo
   Codes of malfunctions of the OBD-II system
   Control unit of the engine (PCM)
   Sensors and valves of system of injection of fuel (EFI)
      Replacement of the sensor of provision of a butterfly valve (TPS)
      Replacement of the sensor of absolute pressure of air in an inlet collector on models since 2001
      Replacement of the sensor of the measuring instrument of a consumption of air (MAF) on models since 2001
      Replacement of the sensor of air temperature coming to the engine (IAT) on models till 2001
      Replacement of the sensor of temperature of cooling liquid (ECT)
      Replacement of the sensor of an angle of rotation of a bent shaft (CKP)
      Replacement of the sensor of position of the camshaft (CMP) on models since 1998
      Replacement of sensors of oxygen (O2S) and fuel-air mix (A/F Sensor)
      Replacement of sensors of a detonation
      Replacement of the sensor of speed of the car (VSS)
      Replacement of the valve of a control system of the frequency of rotation of idling (IAC)
   System of compulsory ventilation of Carter (PCV)
   System of recirculation of the fulfilled gases (EGR) on models since 2001
   System of catching of vapors of fuel (EVAP)
   Catalytic converter
8. Coupling
9. Transmission
10. Driveshaft and shaft of the drive of driving wheels
11. Brake system
12. Suspension bracket
13. Steering and running gear
14. Body
15. Electric equipment
Schemes of electric equipment


Toyota RAV4>> The control system and decrease in toxicity of the fulfilled gases>> Sensors and valves of system of injection of fuel (EFI)>> Replacement of sensors of oxygen (O2S) and fuel-air mix (A/F Sensor)
On cars the system of onboard diagnostics OBD-II in a control system of the engine which has feedback between the sensor of oxygen and the control unit of the engine (PCM) is installed. It is reached due to installation of primary sensor of oxygen or the sensor of fuel-air mix before catalytic converter and the secondary sensor of oxygen behind converter. Depending on the content of oxygen in the fulfilled gases the sensor of oxygen induces tension corresponding in size. On the basis of these data the control unit of the engine changes time of opening of nozzles and a ratio of fuel in fuel-air mix. In order that there was a full combustion of gas mixture and in the fulfilled gases there were no harmful substances, 1 part of fuel has to fall on 14,7 weight parts of air.
Defining composition of the fulfilled gases before and after converter, PCM defines efficiency of converter.

Fig. 7.16. An arrangement of sensors of oxygen on models since 2001: 1 – electric sockets; 2 – oxygen sensor (block 2, sensor 2); 3 – oxygen sensor (block 1, sensor 2)


Primary (in the direction of the fulfilled gases) the sensor of oxygen is located in a final collector or in an exhaust pipe, and secondary — behind catalytic converter (fig. 7.16) .

       PREVENTION
Do not mix sensors of oxygen and fuel-air mix. They are similar on appearance, but work differently and have various operational characteristics.

Like the oxygen sensor, the sensor of fuel-air mix transforms information to the output tension transferred to the control unit of the engine. The size of a signal is proportional to the air/fuel mix relation in a stream of the fulfilled gases. The sensor of fuel-air mix changes output tension from 3,3 to 3,0 in depending on an oxygen proportion in a stream of the fulfilled gases. Like the oxygen sensor, the sensor of fuel-air mix begins to work normally only after warming up for what install heaters on sensors.
At service of sensors take the following precautionary measures:
Sensors of oxygen and fuel-air mix have constantly connected braid with wires and the electric socket which are not separable from the sensor. Damage of a braid with wires or its removal or the electric socket can break operability of sensors.
Exclude hit of dirt, lubricant and other substances on sensors.
Do not use solvents for cleaning of sensors.
Do not throw and do not strike sensors.
As sensors are installed in a final collector or an exhaust pipe, they burn therefore it is very difficult to remove them on the cold engine.
You make replacement of sensors of oxygen (O2S) as follows:
To exclude probability of damage of sensors, launch the engine for 1–2 min., then switch off it. Removal of sensors is facilitated now, however at the same time it is necessary to be careful not to burn about a hot final collector and an exhaust pipe.
Switch off ignition and disconnect a wire of "weight" from the rechargeable battery.
If it is necessary to remove the secondary sensor, lift the car on the elevator.

Fig. 7.17. An arrangement of primary sensor of oxygen on the block 2 on models since 2001


Primary sensor can be replaced, without lifting the car (fig. 7.17) .
Disconnect the electric socket located on oxygen sensor wires.

Fig. 7.18. An arrangement of the secondary sensor of oxygen on the block 1 on models since 2001


Turn out the sensor from a final collector or an exhaust pipe (fig. 7.18) . For a reversing of the sensor use a cutting cap key.
Apply antiprigarny structure which will facilitate the subsequent otvorachivaniye of the sensor on a sensor carving. The carving of the new sensor is already covered by antiprigarny structure. Screw the sensor and reliably tighten it.
Connect the electric socket of the sensor.
Lower the car.
You carry out installation of the sensor to the sequences, the return to removal.