Oxygen Sensor - Porsche 944 Workshop Manual

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Fault, Fault Code
Test Point 8: Sensor signal test

Oxygen sensor

Sensor voltage can be read direct in the "actual value" menu with a 9288
(V)
System Tester.
(sensor signal)
Fault Code 1_24
If not:
Disconnect oxygen sensor plug. Connect a digital display
voltmeter on the sensor end test connection (sensor
voltage signal) and ground.
Start and run engine warm so that the oxygen sensor
reaches its operating temperature. A change in the
voltage signal must be displayed when the mixture is
richer, e.g. by accelerating.
Display on voltmeter:
approx. 150 mV - 900 mV (depending on composition of mixture)
Remarks:
If the control unit recognizes an oxygen) sensor voltage signal of more than
1 V or less than 0.1 V, the control unit will switch over to operation without
oxygen sensor (short or break).
If regulation does not work and the sensor voltage signal is okay, check the
coding of the control unit before replacing the control unit.
Test Point 9 Intake air temperature can be read direct in the "actual value" menu with a
9288 System Tester.
Air temperature
sensor
If not or when a non-plausible value is displayed:
NTC I ( )
Fault Code 1_25
Connect an ohmmeter on terminal 44 and terminal 26 of the disconnected
DME control unit plug.
Display at:
D 24/28 - 16
Fuel System - Electronic Control
Possible Causes, Elimination, Remarks
0° C = 4.4-6.8 k
15-30°C = 1.4-3.6 k
40° C = 1-1.3 k
944 S/944 S2
DME - Diagnosing/Troubleshooting
Printed In Germany - XXI, 1989