Hello,
I have a 98 Ram 1500 with the 5.9L V8 gasoline engine. I just recently had a new engine put in, and decided to install a new upstream oxygen sensor hoping that it would increase my fuel economy. I was getting around 13.2mpg or so. Now, I get around 10mpg. I was wondering, my downstream o2 is the same one that came from the factory with the truck. Does the downstream sensor have any effect on fuel injection? Lots of people say it is to monitor the cat, but does it affect fuel economy as well?

Thanks,
Bryan

 

If the sensor dies altogether, the result can be a fixed, rich fuel mixture. Default on most fuel injected applications is mid-range after three minutes. This causes a big jump in fuel consumption as well as emissions. And if the converter overheats because of the rich mixture, it may suffer damage.
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