EGO sensor tester:

One of the most important parameters in modern motor vehicle management is the air-fuel ratio, since this affects the ‘cleanliness’ or otherwise of the exhaust gases. In fact, the ratio is measured indirectly by the amount of oxygen in the exhaust gases. The sensor used for this is the exhaust gas oxygen (EGO) sensor. This is sometimes called a lambda sensor from the Greek letter lambda (λ) which denotes the equivalence ratio (ratio of actual air-fuel mixture to ideal air-fuel mixture). The correct operation of this sensor may be tested and monitored with the circuit described in this article.