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 Scheme 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 Scheme 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 Scheme 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. |