Discovery 2 with 170k All this is revolving around p0150 code I recently started getting. I have a slightly rough idle and bad mpg now. I have a scanner tool and when I first start the car and let it idle for bit, The volts on the O2 sensors all bounce around like normal. But once I start driving and the car warms up all the way, The front passenger O2 sensor gets locked at .1 volts and the rear one gets locked at .9 volts in the code starts popping up. The sensors Are all about a year old and I've switch them around and the problem continues with just the passenger side even with the driver side plugs on it. I also have a slight air leak from the vacuum lines on the intake manifold for the brake booster plastic line and the rubber one next to it. But I don't know what connectors to get to fix those and seal that up properly. I keep seeing a lot of open-ended threads about this fault code and I'm wondering What you think I should do next?

 

If the sensors are functioning and then they go to .1, it means your bank is lean. What could cause lean bank? Vacuum leak? But only on one bank? Not likely. Faulty injector? That would do it. Have you tried to swap injectors left and right?

 

What's the best way to test the injectors?

 

Other than swapping left to right? You can actually pull the upper intake, remove the injectors, and have a friend spin the engine while you watch/film to see if any are not working. You might want to pull the plugs first and look for which one is light/white - if you have one cylinder lean it will be that one. There are post on here, new sets of injectors are not very expensive, I have had a bad injector before. It is rare but does happen.

 

I threw some injection cleaner in the tank and after a couple days code is gone! All o2s are reading perfect now.