Bendix

Oxygen Sensor (Lambda Sond):

Used by the fuel injection ECU:

PURPOSE AND LOCATION
Under normal conditions, the optimum air/fuel mixture ratio is 14.7kg air to 1kg fuel. The ratio is monitored by measuring the exhaust gas oxygen content. The oxygen sensor (lambda sond) senses the oxygen content in the exhaust and sends a voltage signal to the fuel injection ECU.
The oxygen sensor is mounted in the exhaust manifold about 6in (15cm) in front of the catalytic converter.

CONSTRUCTION
The sensor consists of a steel housing, glass seal, sensor, titanium-dioxide covered tip and its protective sleeve.

Operation Of Oxygen Sensor (Lambda Sond):

OPERATION
This particular model of oxygen sensor is known as a "semiconductor sensor". Its resistance changes depending on the amount of oxygen remaining in the exhaust gas.
The sensor operates only within a certain temperature range of approx. 392 - 1530°F (200 - 850°C). It is electrically heated to reach its operating temperature as fast as possible.
When the ignition is turned ON, current is sent to the PTC (positive temperature coefficient) resistor R1 (heater) whose resistance increases as temperature increases. The current then separates with part going to resistor R2 and a constant 1.2V beeing feed to the oxygen sensor (Ti O2).
The exhaust gases reach the outer surface of the oxygen sensor tip via the openings in the protective sleeve, this changes the resistance in the sensor, altering the voltage read by the ECU.

SIGNAL
The sensor signal voltage is in direct proportion to the amount of oxygen in the exhaust gases. This depends on the air/fuel ratio. A "Lambda" value of 1 represents the theoretically perfect ratio. A rich mixture results in a higher voltage then a lean mixture.
The voltage signal sent by oxygen sensor varies between 0.1 - 1.2V. The fuel injection ECU uses this information to adjust the amount of fuel injected.
The oxygen sensor signal gets disregarded by the ECU at and immediately after start-up and at full load (throttle switch position).