Boxster S (986) F6-3.2L (2001)
Diagnosis of Universal Lambda Sensor - UEGO
Diagnosis of Universal Lambda Sensor - UEGO (911 Turbo)
General Description
Offset
Incorrect lambda measurement due to shunting effects. Diagnosis: Lambda-offset of downstream control exceeds threshold.
Heater Coupling
Low impedance coupling between heater and sensor can cause lambda modulations with the heater pulse rate.
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.
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