S2 V8 Ecu Not Reading O2 Sensors?

My 2001 V8 Disco has a running problem on gas and petrol. On petrol it runs too rich and on gas it runs rough. The fault code that comes up on diagnosis is that both O2 sensors are not there. They have both been changed and the code is still there. The sensors have been tested out of car and work fine so we re wired the sensors. We still have the same fault and there is no change in the running. Could this be a problem with the ECU itself? Has anyone seen this problem before?

hi had this fault on a p38 range rover import but that was due to not having cats fitted as not needed in aussie but failed its mot over here,not come across on a disco it might be possible to turn the sensors on if ecu does not reconise them,did it run ok before, when did the fault start was it pre gas fitting or after,can you get it on the computor to see if the sensors go through warm up process or does the computor not recognise the car configuration held in the ecu,i will have a look in my manuals to see if i can find a link,tiga

Hi reading the rave disc at the engine ecu there should be a 24 pin connector which controls the oxygen sensors at at least 4 of these pins there should be 0-5 volts reading changing with differing temps at sensors, pins 14/15/16/17 all 0-5 volts,if the car is not programmed to the correct market it could have sensors turned off but first i would check for feeds coming out of ecu if you need a total pin count from 1-24 give me a shout,well heres a thought it says that 02 sensors dont work on open loop fueling this beeing cold start hot start wide open throttle and acceleration the ecm cotrols this through programmed statergies,closed loop fueling uses the 02 sensors when they are at correct temperature,the ecm also relies on info from coolant temp sensor maf/iat sensor and tp sensor,would check out puts from ecu and continuity of the wiring first as they should have a voltage always hope some of this helps,tiga

Thanks tiga. This has been usefull information. The car does respond to a diagnostic computer and tells us the O2 sensors are not working at any time. This all started when the engine was replaced after having a cracked block. We have decided to send the ecu away for testing and repair if needed so as we can at least rule that out. Thanks again, G.

No problems please let me know if i can do anymore,1 thing that just come to my mind is make sure that the car has not lost its market programming i have seen this before on a TD5 they changed the engine and it would not start when i looked through the car configuration files it was listed as an auto v8 and a few other things that were incorrect so once ecu tested i would just have this checked,i take it that harness checks out ok as i think there maybe connectors at back of head cheers tiga