The sensor for the 1983-1984 Volvo 240 is $35.00. It is a genuine Bosch direct replacement from FCP Groton. This is a great price as some of the Bosch sensors for some of the other model Volvo cost over $100. It is another $8.00 to $10 to buy an oxygen sensor socket. These are available at most auto parts stores and with the addition of some PB Blaster should make the job much easier. My sensor should arrive today. I will let you know if I experience improved engine operation and better MPG.

I tested my sensor as well it appears to work as outlined but only when the engine is at operating temp. I think this sensor has a 12 volt heating element that may be bad?