Lambda Control Test

Although the lambda control function can be checked relatively easily, it requires a matching wire and an ammeter, which many electronics enthusiasts have. Alternatively, the test can be performed with an exhaust gas analyzer to measure CO content. The procedure is described below:

TEST PROCEDURE

The test must be performed with the engine at operating temperature.

Disconnect the connector of the pressure regulator and connect a test adapter made from two suitable connectors and a piece of wire between the wiring harness and the pressure regulator.

Disconnect one of the matching wires and connect it to the measuring instrument (milliampere range).

Start the engine and let it run at idle.

Record the reading.

Pull out the oil dipstick.

The control circuit current should increase.

If not, one of the lambda control components is faulty.

In this case, try disconnecting the connector from the lambda sensor and hold the green wire to the control unit to ground for approx. 20 s.

If the control circuit current now changes, the KE-III-Jetronic control unit is OK, but the lambda sensor is faulty – replace it.

If nothing happens, the fuel injection control unit is faulty.

Note: The basic prerequisite for functioning lambda control is correct basic idle adjustment, which means that the CO content is within specification. Otherwise, control will constantly remain at one of the limits of the specified range. The same conditions occur if the mixture is excessively lean due to unmetered air.