I just purchased my first Land Rover last week. It is a 2001 Discovery Series II SE. My check engine light came on so i went to AutoZone and had them read the code which came out P0150. Told me that the o2 sensor was bad on bank 2. Where is bank 2? I dont know much about the Land Rover yet but does the Series II have 2 or 4 O2 Sensors? should I change them all or just the one?

 

Bank one is your driver's side, and bank two is your passenger side. You have four o2 sensors all-together. Sensor one is before the cat, and sensor two is after the cat.

It's best if you replace all four at once, if you just replace one, it may throw a code because you're using a new sensor with old ones. You can get new ones from www.roverparts.com , that's where most of us go. I'm sure others will chime in with other places that they've gotten them from.

 

You could, in theory replace just the one sensor that is throwing a code, but there is a chance the other upstream sensor could fail soon, as they are both probably the same mileage. The upstream sensors (before the converter) control fuel input to the engine. All the downstream (after converter) sensors do is monitor converter efficiency (tell the computer if the converter is working).

I replaced both upstream sensors on mine recently as it was close to 100k miles (no codes), just to increase fuel economy (1-2MPG gain), but I have no plans to replace the downstream sensors until they throw a code, as they do nothing more than monitor the converter.

 

I would suggest you do all 4 02 sensors, lets forget about the codes, when 02's get old, they don't do as good a job in balancing your air/fuel ratio between the 2 banks, hence, bad miles and less power.

 

I found aftermarket parts on EBay. Do you recommend getting aftermarket or just buying from Land Rover? Also i have found used parts on ebay, do you recommend buying used sensors?

 

Why would you install some one elses warn out 02's???????????????????
Stay away from the generic one that you have to rewire and buy what is needed, Amazona has probably some of the best prices.

 

Is there a trick to disconnecting the front 02 sensors? I have a 2004 Disco II and am having a hard time disconnecting the eltronic connection. If I had the hands of a 5 year old it would be easier.