Diagnostic tips for workshops

We recommend checking the function of lambda sensors every 30,000 km and/or on every exhaust emissions check. In the process, there are different, complementary methods.

There is more than just the efficiency of the catalytic converter that depends on the functional capability of the lambda sensor. Faulty or defective sensors cause a series of problems, such as

  • increased fuel consumption,
  • failure of and damage to the catalytic converter,
  • poor driving characteristics and
  • failure to pass the emissions testing.

For these reasons, we recommend having the function checked every 30,000 km and/or on every exhaust emission check. In the process, there are different, complementary methods:

Testing with an oscilloscope

The oscilloscope test is the most accurate of all methods. It shows minimum and maximum voltage, the response time and the period. When performing this test, the manufacturer's specifications must be observed.

Test procedure:

Visual inspection

A visual inspection often provides the initial clues for a possible malfunction. Inspection points for the workshop are:

Heat resistance:

If it is above 30 Ω, the sensor is defective.

Cables:

Are the cables or the adapter broken?
Is the cable seal intact?
Has moisture penetrated into the plug?
Are the adapter contacts OK?
Is the cable routeing too tight?

Sensor:

Does the sensor show any visible damage?

Note:

There are special sensors for every vehicle - therefore they may only be replaced with identical sensors.