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How to Test Oxygen Sensors

oxygen sensors

MVS Forums member bluenote 27 feels like his Volvo 240 isn’t getting its maximum km per L of gas and he has a hunch that it might be related to the vehicle’s oxygen sensors. He raises many important questions relating to the issue. One of which is aimed at the cost of a single wire vs 3 wire sensor. What are your thoughts on oxygen sensors and how to test them properly?

I’ve been reading up on O2 sensors and their effects on fuel efficiency. I feel like my 240 isn’t getting it’s maximum Km per L of gas and was thinking that I could have a malfunctioning sensor. Is there a way to know if you’re O2 sensor is malfunctioning? If installing a new O2 sensor in my 1984 240 should I install a single wire or a three wire sensor? I know that the three wire sensor makes the sensor effective more quickly – but it is also three times the price. Since my car is old I was hoping to just install a single wire O2 sensor…. will that work?

MVS Forums member Bramdeman replied:

Simply unplug the o2 sensor and go for a drive, if it behaves any different (popping in the exhaust, rough idle, stumbling engine) than the sensor was fine. If it makes no difference its probebly dead. One more way, take it out of the exhaust and shake it, if it rattles 9 out 10 times it’s dead. I would simply replace the sensor with the same kind that was in it. I don’t think it will work any other way. A Bosch parts store will tell you for sure.

How to Test Oxygen Sensors


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