Ok, here we go. For a few weeks my exhaust was blowing and upon checking around it was the cat that had a clean split aound it a couple of inches long. The car drove fine and still does. Although after a few weeks the engine management light came on (EML). So i took the car into a exhaust specailist who welded the cat. The EML remained on, so i took the car to the local stealers. They ran the car through the diagnostics, and came up with these faults
P0051 - HO2S heater control circuit Low Bank 2 Sensor 1
P0031 - HO2S Heater control circuit Low Bank 1 Sensor 1
P0037 - HO2S Heater control circuit Low Bank 1 Sensor 2
P0057 - HO2S Heater control circuit Low Bank 2 Sensor 2
P0134 - O2 Sensor circuit No Activity Detected Bank 1 Sensor 1
P0154 - O2 Sensor circuit No Activity Detected Bank 2 Sensor 1
P0140 - O2 Sensor circuit No Activity Detected Bank 1 Sensor 2
P0160 - O2 Sensor circuit No Activity Detected Bank 2 Sensor 2

Now at the side of the report with a pen the enginer has wrote O2 sensors P0134 P0154
HO2S Control circuit P0030 P0050 Then still in his handwriting it also reads two other faults P0030 P0050 two faults still present with little lines pointing at P0134 and P0154.

I am handy around cars in terms of fixing and replacing things when I know what ive to replace but I dont quite follow where my next step is with this-do i replace all the sensors or only some? Or because its pointed to both banks would it be a fault somewhere else? Or....?

Open to all suggestions and help. Many thanks Fraser

My initial thoughts would be that, now the cat has been welded, clear the faults on the ECU and check again in a week or so to see if any faults have returned.

I recently got one of THESE code readers to save taking it to a steeler. At least then you know whether the faults have returned of not and they cost less than one plug-in at the steelers.

If the faults do return then start with the sensor connections, make sure they are connected and even clean the connections. Then check the wiring to make sure it's in good order.
If all this is OK and the faults are still there, then look at replacing the sensors. I would start with the O2 sensors first as they are reporting no activity.  

How easy are the O2 sensors to replace? [img]http://www.fuelly.com/driver/rob2529/range-rover[img/]
04, 4.4V8, Vogue Oslo Blue with LPG.
"You can sleep in your car, BUT you can't race your house!!!!"

If something can't be fixed with a hammer....... You have yourself an electrical fault!

Rears are easy , fronts are hard (difficult to get the spanner in) especially if the thread is b gerred. They have connectors that are relatively easy to pull apart. When installing new ones, I suggest to use some copper grease on the thread as stainless steel threads are prone to seizing. MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

Personally, I would get the errors reset first.then if you can get the adaptive values of the ecu reset too. ( may take a more advanced diagnostic tool for that )

That way you are making the ecu learn from scratch base zero to adapt from, rather than the well out learned values it currently has.... Even still, it should adapt back very quickly ( mine seemed to adapt within the first mile of a complete reset on a warm engine)

I wouldn't replace your sensors just yet ... You don't know for sure they are duff yet. Even a simple tool off eBay will let you see if they are reading anything from the sensors when running.... And it's still cheaper than a single O2 sensor.

Unusual to see both banks with errors .... May point to a common issue between both sides of the engine ... Like the air flow sensor.... Again, a simple diag tool will show the air flow reading and inlet temp.

If you find that you have no flow reading, or inlet temp reading, that can create O2 errors as well. V8 or else ...

Im thinking of buying the sensors, as it was a Land Rover dealer that done the diagnostics and cleared everyithing so sensors under the fault code P0134 and P0154 are still not reading anything. Does anyone have part numbers for these sensors? Both are number 1 sensors on either bank.

Fraser

Both are #1 sensors on each bank ...

not being funny ... but after the exhaust was welded ... have they been plugged back in? V8 or else ...

I havnt actually checked. But the fault appeared before the welding was done.
Still need to get my hands on the part numbers though. I can find them online but can't distingush between which is which.

Fraser

An update on this. So just after my last post I discovered my PCV hoses had failed, so replaced those along with the valve etc. lso replaced the two front O2 sensors, spark plugs , oil and filter, and finally the MAF. Unfortunately the EML has still not disappeared. I reset the engine ecu using an IIDtool. It returns everytime. Although the engine is running much smoother now after the work which has been done it is only getting about 11-12mpg. Also the nearside bank (bank2 i believe) is running rich and is producing soot under throttle. I did however buy and fit universal O2 sensors, which im now regretting. As being non OEM throws doubt into them working.
Ok so my queries are, Does anyone have the part numbers for the OEM O2 sensors? As im thinking of replacing them again with OEM.
And what all can contribute to only one bank running rich?
Would a full reset of the engine ecu still be adviseable as Fisha says? Fisha, can you recommend anyone?
I have a severe dislike to taking my car to the large dealer in our area beginning with T and ending in aggarts after useless help from them in the past.
Remember my car is 4.4 petrol. I should say that when I intially reset my EML the car seems to smooth out at idle. But goes slightly rough again once EML returns.

Many thanks Fraser

1 bank will run rich if the O2 sensor on that bank is giving incorrect information to the engine computer.
Switch the O2 sensors side-to-side to see if the problem follows the sensor.
If so, the problem is the sensor. Jim
2000 NAS HSE
2005 NAS HSE

Thanks Jim2RRs. I'll try and get out to do that later today, although the weather has taken a turn for the worse. Is it always the sensors pre-cats that can affect over fueling, or do the sensors after the cats also contribute to this?

Thanks again. Fraser

You can actually swap the connectors so you don't have to remove/re-install the sensors themselves  MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

Did you replace the MAF with a genuine one ? V8 or else ...

Yes replaced the MAF with a genuine one.

Yeah - I replaced with genuine after trying an aftermarket one ... costly mistake .. but lesson learned I suppose.

Fraser... I reckon that once you've got the physical bits working ( O2 sensors / whatever ) by reseting the engine mgmt light with the IID tool, the engine should be able re-adapt quickly and have no need for a full adaption value reset. The key is feeding the engine the right values from sensors ... the ECU seem very sensitive to this.

I agree with Jim as well that swapping the sensor to the other bank will indicate whether the problem moves with the sensor or stays with the engine bank.

At this sort of diagnosis level ... the faults and codes are OBD2 compliant stuff ... hit ebay and get a cheap Elm327 OBD2 reader kit which will come with some pretty crap software which allows you to see the live values from the engine ECU in terms of O2 readings, MAF etc etc. ( that is if the IID tool doesn't already do that??? I have no experience of it ) Elm327 stuff is good enough to be able to see what the engine is thinking, and would quickly show whether an O2 reading is way off the mark ( i.e. duff )

As for the pre-cat / post cat O2 sensors ... As far as I understand it, the pre-cat sensor is the one that reads the burnt fuel mix ratio coming out the engine, and its this reading that the ECU will do any fuel trimming or adaptions from. ( The reading goes in a waveform above and below the perfect fuel mix value as the ECU constantly adjusts up and down to get towards the perfect value)

The post cat sensor is basically there to see that the cat convertor is doing its job, and that the fuel mix ratio is much closer to the right value ... i.e. the waveform of the pre-cat, but closer to perfect value. If the post-cat sensor goes out of whack, its not going to make the ECU change its adaptions at all, at the worst case it would flag up the engine ECU light saying something is wrong, but not much else. V8 or else ...