Thread: Lambda (oxygen) sensor retrofit

Originally Posted by glenhendry

Rave says (Fuel V8, section 19, page 54) that for post 99 vehicles, pre-cat sensor connectors are orange and post cat sensor connectors are grey.

I just bought two of these (Auto Parts Giant - Land Rover ARBL960903) from the US and installed them, but they have the grey connectors, and the ones I removed which I assume are OEM have orange plugs. The reason I checked RAVE is because these new sensors are always showing 0v on ODBII scanner (Android 'torque' app). My fuel system is always in 'open loop - low temp' though, regardless of the engine temp (which sits at 92c once warm)

So I have finalised this. The new grey connector sensors are indeed after-cat sensors, as they showed 0v on the OBD readout. I put the old ones (orange connectors) back in one at a time and they instantly started showing values (between 0.1v and 0.9v) and then the fuel system readout on OBD went to "closed loop - using o2".

So I am happy, the O2 sensors are working again, and I am back on closed loop operation. However, be careful when you buy o2 sensors, as the website I bought them off clearly mislabelled them as pre-cat o2 sensors and while they fit, they dont work.

Originally Posted by glenhendry

Also note that if ECU fault codes exist, it can put the ECU into a kind of limp mode where it goes into open loop fuel mode. This happened to me last weekend when my air intake popped off while four wheel driving, the MAF sensor fault code was thrown and then even after I repositioned it, the ECU stayed in open loop mode until I cleared the fault codes after which time it returned to closed loop operation.

For completeness, this open loop operation was more likely to have been caused by my using LPG to get out to the 4wd area on the highway, and then switching to petrol while wheeling as per this thread: http://www.aulro.com/afvb/showthread...75#post1573475.