Description
(1) oxygen sensor
"a" 4-way black connector
Supplier: NGK
Role
The oxygen sensor determines the richness value of the oxygen in the exhaust gases, checking that the catalytic converter is operating correctly and resetting the richness following any drift in the injection system and in the catalytic converter
Function
The oxygen contained in the exhaust gas is compared with the oxygen contained in the oxygen sensor taken from the ambient air in order to deduce a richness value
If the difference between the oxygen contained in the exhaust gas and the oxygen contained in the oxygen sensor is significant, the mixture will be "rich", if the difference is slight, the mixture will be "lean"
The oxygen sensor compares the composition of the mixture injected with the stoichiometric dosage (lambda = 1) in order to deduce an output voltage
NoteLambda signal ratio = weight of air admitted/theoretical air weight
Electrical features
"b" rich area
"c" poor area
The "rich" or "lean" mixture information is given by 0,1 to 0,9 V voltages
Lean mixture = approximately 0,1 V (Lambda higher than 1)
Rich mixture = approximately 0,9 V (Lambda lower than 1)
The engine management ECU regulates the richness by varying the injection time to get as close as possible to the stoichiometric dosage (lambda = 1)
The oxygen sensor contains an internal heating device which enables the operating temperature to be reached rapidly (+ 300 °C)
| channel number | allocation of channels of connector |
|---|---|
| 1 | +12 volts supply (Oxygen sensor heating) |
| 2 | oxygen sensor heating control |
| 3 | signal (-): oxygen sensor |
| 4 | signal (+): oxygen sensor |
Learning / initialisation
Programming is necessary if the component is replaced