Vauxhall Workshop Service and Repair Manuals

Lambda Sensor (Simtec)  

Measurement:	Plot of voltage signal for the Lambda sensor.
Check objective:	Operational check

Preparation  

Engine oil temperature > 80 ° C. Switch off the engine and ignition.  

Connections  

INPUT A	COM/TRIGGER
Connect the red measurement lead with the blue adapter filter to pin D of the plug connector for the Lambda sensor. Connect ground lead to ground.

Procedure  

Start the engine and allow it to idle.  

Reference Curve

Ageing of the Lambda sensor can affect signal frequency for particular measurements. The frequency is thus reduced as the sensor becomes older.  

Fault Diagram 1   Symptoms:   Control frequency too low when engine is idling and under partial load.   Guideline: At least 5 rising and falling slopes must be visible (for a horizontal scaling factor of 2s/DIV).

Possible Causes	Countermeasures
Faulty Lambda sensor	Check the O 2 circuit as specified in the checking procedure. If necessary, replace the Lambda sensor.

 

Fault Diagram 2   Symptoms:   Lambda sensor voltage consistently too low. Maximum value: < 2.4 V

Possible Causes	Countermeasures
Mixture too lean	Check and repair electronic engine system as specified in the checking procedure.

 

Fault Diagram 3   Symptoms:   Lambda sensor voltage consistently too high. Maximum value: > 2.4 V

Possible Causes	Countermeasures
Mixture too rich	Check and repair the electronic engine system as specified in the checking procedure.