PRE-RELEASE
Front heated oxygen sensor (592)
| Front heated oxygen sensor (592) |
| Location |
Front heated oxygen sensor (592)
| Main task |
For exhaust purification to work well, the catalytic converter requires an air/fuel ratio of exactly 14.7:1. The system is therefore equipped with an oxygen sensor mounted in front of the catalytic converter. The front sensor is known as oxygen sensor 1 or O2S 1.
| Type |
| Connection |
| Pin No. | Signal type | Description |
| 1 | Power supply, B+ | Preheating power supply from preheating relay. |
| 2 | Control | Preheating's control. Preheating is grounded by ECM pins 40(B) and 57(B), which control the preheating current. |
| 3 | Ground | Oxygen sensor's signal ground. Connected to ECM pin 6(B). |
| 4 | Signal | Oxygen sensor's signal. Connected to ECM pin 5(B). |
To quickly yield voltage after start, the oxygen sensor must be preheated. Grounding of the preheating circuit is pulse width modulated so that preheating output can be regulated.
The control module estimates exhaust temperature based on load and engine speed. If exhaust temperature is high, preheating is switched off so as not to damage the oxygen sensor.
When exhaust passes the oxygen sensor, the oxygen content is gauged through a chemical reaction. The oxygen sensor's output voltage is proportional to the actual oxygen content. The oxygen content describes the composition of the air/fuel blend. If the engine receives a richer fuel blend than normal (lambda under 1), the oxygen sensor's output voltage will be approx. 0.9 V. If the engine's fuel blend is leaner than normal (lambda over 1), the oxygen sensor's output voltage will be approx. 0.1 V.
The sensor voltage value is changed very quickly when lambda exceeds 1.
The closed loop factor is 1.00 when closed loop is inactive. As soon as closed loop is activated, oxygen sensor voltage is allowed to affect the closed loop factor. If the oxygen sensor yields a voltage lower than 0.50 V (lean blend), the correction factor will slowly increase, i.e. more fuel will be injected. Conversely, the correction factor will slowly decrease if the oxygen sensor's output voltage is greater than 0.50 V.
