Description
(1) proportional oxygen sensor
"a" oxygen sensor connector 6-way
Supplier: NGK
Role
The proportional oxygen sensor measures the oxygen content of the exhaust gases relative to the ambient air
The proportional oxygen sensor determines the oxygen content of the exhaust gas and deduces the exact richness of the mixture
Function
"b" exhaust gas supply channel
(2) electrode
(3) pumping cell
(4) measuring chamber
(5) Nernst cell
(6) reference cavity
(7) heating resistor
The oxygen contained in the oxygen sensor is drawn into the exhaust gases by a pumping current and retained in the measuring chamber (4)
The Nernst cell compares the oxygen content of the measuring chamber (4) with the oxygen content of the reference cavity (6)
In order to obtain a lambda of 1, the oxygen content of the measuring chamber (4) must be equal to the oxygen content of the reference cavity (6)
The value of the pumping current is linked with the flow of oxygen originating from the exhaust gas, necessary in order to regenerate the oxygen in the measuring chamber (4) and have a lambda of 1
When lambda is higher than 1 in the measuring chamber (4), the pumping current is positive, the excess oxygen contained in the measuring chamber is taken off to be sent to the exhaust gas
When lambda is lower than 1 in the measuring chamber (4), the pumping current is negative, the oxygen which is lacking is taken from the exhaust gas and sent to the measuring chamber
When lambda is equal to 1, the Nernst cell supplies a voltage of 0,45 V
The electrical output signal that is proportional to the oxygen content is obtained by measuring the current necessary for the pumping cell to regulate the oxygen content in the measuring chamber
Electrical features
Reference values
"A" pumping current power (mA)
"B" lambda
"C" rich area
"D" poor area
| designation | value |
|---|---|
| maximum supply voltage: heating resistor | 7,5 V |
| value: heating resistor | 3,2 ± 0,8 ohms |
| maximum supply voltage: oxygen sensor | 10,8 V |
| activation time: maximum | 10 s |
| value of the LAMBDA: measured | 0,8 ≤ lambda ≤ infinity |
| tolerance on the lambda value measured | ± 4 % |
| temperature of the exhaust gas admitted | +/- 980 °C |
| maximum pressure of the exhaust gas admitted | 2,5 bars |
Connections
| channel number | allocation of channels of connector |
|---|---|
| 1 | pumping current |
| 2 | earth |
| 3 | heating (-) |
| 4 | heating (+) |
| 5 | compensation resistor |
| 6 | Nernst voltage |
Programming/initialisation
Programming is necessary if the part is removed/refitted; refer to the diagnostic tools documentation: programming/initialisation