LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Porsche >> 1983 >> 944 Automatic >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> DME Digital Engine Control >> Operation >> Data Sensors >> Oxygen Sensor
October 30: LEMON manuals on a temporary server, it is slow and having issues, download the manuals you need! Later in November we will switch back to the fast server.

Oxygen Sensor

This sensor is mounted in engine exhaust stream, in front of catalytic converter. It supplies a low voltage (under 1/2 volt) when fuel mixture is lean (too much oxygen) and a higher voltage (up to 1 volt) when fuel mixture is rich (not enough oxygen).

Oxygen sensor must be hot (over 480°F/250°C) to function properly and to allow ECU to accept its electrical signals. The oxygen sensor measures quantity of oxygen only.

California vehicles are equipped with a special electrically heated oxygen sensor. This oxygen sensor reaches operating temperature sooner and also begins to function earlier. The heated oxygen sensor has 3 wires, 2 for the heater element (power & ground), and a single wire for the oxygen sensor signal.

The heating begins with ignition on (via fuel pump & DME relay terminal 87). The plugs from the sensor to the wiring harness are located near the flywheel sensor plugs (speed, reference mark).

NOTE: No attempt should be made to measure oxygen sensor voltage output. Current drain of conventional voltmeter could permanently damage sensor, shift sensor calibration range and/or render sensor unusable. Do not connect jumper wire, test leads or other electrical connectors to sensor. Use these devices only on ECU side of harness after disconnecting sensor.
scientia non olet · About LEMON Manuals