Vauxhall Workshop Service and Repair Manuals

Lambda Sensor (Not Simtec)  

Measurement:	Plot of signal voltage for the Lambda sensor.
Check Objective:	Checking Operation.

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 filter adapter to the plug connector for the Lambda sensor.
MULTEC
Pin 1, except 6 VD 1 engine to pin 2. Connect the ground lead to ground.
MOTRONIC
Pin C, except Motronic 1.5.5 to pin 4. Connect ground lead to ground, except Motronic 1.5.5 to pin 3.

Procedure  

Start the engine and allow it to idle. If either little or no voltage variation can be detected, the engine speed must be slightly increased.  

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 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: < 450 mV

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

 

Fault Diagram 3   Symptoms:   Lambda sensor voltage consistently too high. Maximum value: > 450 mV

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