Lambda Testing W/ Volt, Ohm and CO Meter

Fig. 158 CONNECT CO-METER:

To test the Lambda sond, all potential problems influencing a Lambda sond reading (ignition, fuel injection, intake and exhaust system etc.) must be checked and corrected.

The Lambda sond can be tested as follows:
1. Connect a CO meter. Fig. 158.

Fig. 159 CHECK LAMBDA SOND FUNCTION:

2. Warm up engine until it reaches operating temperature.
3. Disconnect Lambda sond connector. Ground the wire leading to the control unit. Fig. 159.
4. CO content should increase to indicate good wiring and control unit. If the CO content does not increase, check wiring to control unit, repair or replace as needed.
5. Connect voltmeter to Lambda sond. Voltmeter should deflect, indicating that the Lambda sond is operating correctly. At the specified CO content (see "SPECIFICATIONS" > "MECHANICAL SPECIFICATIONS") the voltage should be about 0.3 - 0.7 V.
6. If the reading is different, replace and retest with new Lambda sond.
7. Assemble Lambda sond connector.


Testing Lambda sond heating element:
8. Connect an ohmmeter to the heater wires (two-wire connector). The pre-heating resistance should read:
COLD LAMBDA SOND (20°C = 68°F) 3 ohms
HOT LAMBDA SOND (above 350°C = 662°F) 13 ohms
9. If the ohmmeter reading is incorrect, replace and retest with new Lambda sond.