911 Turbo AWD (996) F6-3.6L Turbo (2001)
Oxygen Sensor: Testing and Inspection
Diagnosis of Universal Lambda Sensor - UEGO
Diagnosis Of Universal Lambda Sensor - UEGO (911 Turbo)
General Description
1. Offset
Incorrect lambda measurement due to shunting effects. Diagnosis: Lambda-offset of downstream-control exceeds threshold.
2. Heater Coupling
Low impedance coupling between heater and sensor can cause lambda modulations with the heater pulse rate.
3. Dynamics - slow response
Due to aging the sensor dynamics can decrease. Diagnosis: Comparison of measured and estimated (model-based) lambda-error caused by
artificial lambda modulation.
4. Plausibility
a. Power Stage - Diagnosis:
Output Voltage of the Power Stage will be switched to >= 4.775 Volts, if a hardware malfunction has been detected by IC.
b. UEGO (Universal lambda Sensor = LSU) not active:
Diagnosis: lambda(LSU) is close to 1.0, but downstream sensor indicates lean or rich mixture
c. Sensor current high (lambda(LSU) lean):
lambda(LSU) > 1.2 while downstream sensor indicates rich mixture
d. Sensor current low (lambda LSU rich):
lambda(LSU) < 0.8 while downstream sensor indicates lean mixture.
Oxygen Sensor Output Voltage Characteristic Diagram:
Monitoring Overview Diagram:
Offset: