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:
Connect a CO meter. Fig. 158.

Fig. 159 CHECK LAMBDA SOND FUNCTION:

-Warm up engine until it reaches operating temperature.
-Disconnect Lambda sond connector. Ground the wire leading to the control unit. Fig. 159.
-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.
-Connect voltmeter to Lambda sond. Voltmeter should deflect, indicating that the Lambda sond is operating correctly. At the specified CO content the voltage should be about 0.3 - 0.7 V.
-If the reading is different, replace and retest with new Lambda sond.
-Assemble Lambda sond connector.

Testing Lambda Sond Heating Element:

-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
-If the ohmmeter reading is incorrect, replace and retest with new Lambda sond.