A/F Sensor Description - Suzuki Grand Vitara 2011 Manual

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1A-13 Engine General Information and Diagnosis: For Petrol Engine Model

A/F Sensor Description

A/F sensor (1), in place of the conventional heated Oxygen sensor-1, is installed in the center of the exhaust manifold

joining section and it consists of a zirconia element (2) which causes the output current to vary according to difference

in the oxygen concentration, a heater (3) which activates the element and an adjusting resistor (4) which adjusts

individual difference of the sensor (J20A engine).

A/F sensor detects oxygen concentration in exhaust gas (9) (A/F ratio of the air-fuel mixture) linearly, ranging from

LEAN to RICH.

ECM (5) controls the sensor heater (3) and keeps the sensor element temperature at the specified level (about 750

°C) constantly so that the A/F sensor is activated in the specified way for accurate A/F detection. When the sensor

element reaches the specified temperature (it is activated), its impedance drops to the specified value (approx. 30 Ω)

by its characteristic.

When a certain voltage (about 0.4 V) is applied between sensor elements in this state, circuit current corresponding to

the sensor element impedance flows in the sensor circuit. ECM detects this circuit current and judges whether the

sensor is in the active state or not. At this time, sensor current is output linearly in the range of +0.01 mA to +some mA

on the lean side and –0.01 mA to – some mA on the rich side. The variation in these ranges depends on the difference

from the stoichiometry A/F ratio, that is, the amount of oxygen between the atmosphere side (6) and exhaust manifold

According to this sensor output, ECM executes A/F feedback (fuel trim) to achieve the target A/F ratio.

The A/F sensor connector (8) is provided with an adjusting resistor (4) ECM detects the adjusting resistance value and

corrects the sensor output current value (J20A engine).

6. Ignition switch

I5JB0A110009-01

S6JB0A1111010

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