Car: 1997 Volvo V70 20V Auto

Problem: Check engine light keeps coming on....diagnostics showed that both Lambda 1 and 2 were faulty. Both items had previously been replaced by the last owner with cheap sensors, so this time around they were replaced with Bosch items.

Car was fine for a week and then the check engine light came on again, this time diagnostics showed that Lamda 2 was at fault

Codes were wiped clean and car ran fine for another week or so and light came on again saying Lambda 2 at fault.

Any ideas whats causing this fault as its clearly not much of a problem as the car drives beautifully and gives good gas mileage and performance is faultless.

I know that Volvo tend to be sensitive on check engine light problems, but any help as to why this is happening or causing the problem would be much appreciated.

 

Could be a wiring problem. What are the inspection/emissions regulations where you live? My 98 has a bad sensor, but the car ran fine and since they don't have emissions where I live decided not to worry about it. Some areas require no MIL(what you can the CEL) when the car is tested.

 

As far as I know, the second O2 sensor is to check whether the CAT Convertor is doing it's job, so it might be your CAT thats dying