Steve, now you're confusing me! I can't recall ANY O2 Heater that was powered on one side and grounded on the other. They have all been controlled on the "ground" side by the ECM.

???

Earlier I mentioned "low voltage" on the ECM side because it is pulse-width modulated, which means pulsed on and off to control. It therefore has some "off time" when the voltage would be high. The result measured with a voltmeter would be some lower voltage, say 2-5v. That's why it's good to compare to the other side for a baseline.

Cheers,

 

No, 'tis me that's confused, I misread JTIS thinking 64E etc was an earth, rather than the relay switched +12V supply so it looks as if OP's measurements could be quite OK as Avos said.



Time to change the sensor?

 

Think you are right, I appear to have a faulty heater on LH (passenger side U.K.) O2 sensor. Did a reading across the two silver pins on the suspect sensor (P1647 code) and got nothing. Checked the other side (P 1646) and it is showing a resistance.

So it seems that the heater on this sensor is faulty, but still doesn't really explain why the 4 injector malfunction codes are coming up also?

Anyway have to change the sensor so will see what happens after that.

First question is what is the best way to remove the old sensor. It looks as though there is a brass thread going into a steel nut attached to the cat. I presume that I have to undo the nut which looks about a 22mm? Can it be done from the top of the engine and without removing the cat itself? Strangely enough it all looks very new down there with the brass shining brightly and no sign of rust on the nut. We shall see, best to give it a good soaking of penetrating oil anyway whatever.

Second question is where is the best place to get a replacement and what is the correct part number for a 2000 XK8. I don't want to pay the earth but on the other hand don't want to fit a cheap one that is going to fail or even perhaps not work in the first place.

I am still not sure which wiring diagram I should be using, have just found out that NAS stands for North American Spec and that ROW is rest of the world, bloody acronyms again! Anyway don't think the wiring comes into replacing the sensor as it will only plug in one way.

Once again thanks for everyone's input.

 

Have been researching these 02 sensors but still not sure which one I need.

Jag say that it is LNE 1684BB but that doesn't seem to correspond with my vin number and seems to be for cars later than my March 2000 car.

Is there only one type of Upstream 4 wire heated o2 sensor? I understand there is wideband and narrowband whatever that is? Mine is definitely 4 wire heated and has the grey connector the same as the LNE 1684BB.

Jag want around Ł120 for their one but there are ones around for Ł30 ish.

Would be good to hear what sensors other forum users have used successfully.

 

The LNE1684BB is the correct upstream O2 sensor for non-supercharged XK8's starting with VIN# 031303, which is the start of the 1999 model year. So as long as it is billed as equivalent, you might be alright with an aftermarket sensor. Just remember ANY non-standard part is a risk of some measure. Some work out, some don't.

Good luck!

 

I've had some tight nuts in my time, this sensor won't shift, limited access doesn't help.

Perhaps if I try it with a hot exhaust and maybe a proper Lambda socket, any other suggestions?

Explosives?

 

I haven't yet had the pleasure of changing one of these but t does seem to be the source of considerable angst.
The problem with a 'proper' socket is that it's got a slot in the side to clear the leads so is weaker than a normal one.
The best 'penetrating oil' seems to be automatic transmission fluid thinned with acetone.
A couple of applications then, as you say, try with the engine hot.
Swearing, I understand, helps considerably.

 

Hmmm, acetone and trans oil is a cocktail I haven't tried before. Sounds pretty potent but I will give it a go.

Funnily enough I was looking at a can of acetone in the workshop last week and wondering why I'd bought it. It's good for removing nail varnish, but I don't seem to wear a lot of that these days!

I've heard that the lambda sockets can be weak. I suppose that as the sensor is kaput I could just cut the wire off and use one of my deep 22mm impact sockets. I'm sure I could tighten the new one enough with an open ended spanner.

I have planned a visit to our local naval barracks to pick up a few good swear words as I don't know many!Armed with these and my new cocktail I will have another go at getting the mother f....r out. Hope there aren't any old ladies from the church passing by during my attempted removal procedure!

 

Here's what Jag has published about the subject......

I've had to do this routine a couple of times, it does help. The cut the wires idea also can help since it needs to be changed out anyway.

Good luck!

 

I don't believe it as Victor would say.

Finally got the N/S upstream oxygen sensor out and went to fit the replacement.

My supplier had assured me that he was supplying the correct part but of course when I went to connect it up the plug didn't fit. It looked almost identical with grey plug and four wire connector but not the right one.

So if you are offered a Cambiare VE381303 for a 2000 XK8, don't bother it doesn't fit. Looking at their application list it appears to be a downstream sensor and they don't seem to list an upstream.

Anyway at least the old one is out and I think I will now go for the genuine Jag part LNE 1684BB, more expensive but still a lot cheaper than some other after market sensors I've seen where they are asking for nearly Ł200, which is some Ł80 more than the OEM part.

 

Bummer! Aftermarket is often a crap-shoot. At least we'll know about that brand. That's why it's cheaper, it's a standard zirconia sensor and not the required wideband sensor.

Keep us posted!

 

Wondered what had happened to you !
What did you have to do to get the old b*gg*r out?

 

Did as you said and left it soaking in the magic cocktail and it came out fairly easily.

Just got to find a replacement now at a reasonable price, but think I'll probably have to go for the Jag one which costs around Ł120. Have already wasted my time with one cheaper replacement. Even if I do find one that physically fits, you still don't know if it is doing it's job correctly.

Can't wait to see what happens to the other injector fault codes once the new sensor is fitted

 

Well here is the offending article, upstream sensor which is actually a Denso unit part no. 192400 3100 which corresponds with Jag part no. LNE 1684BB. All I have to do now is find somebody with the correct one in stock.

 

Jag dealer out of stock but found a website that kept the Denso original sensor. The Denso Europe part no. is DOX0428 which correctly cross references with LNE 1684BB and Denso 192400-3100.

Very helpful and informative website, apparently there is no correct after market sensor available that works in this instance and you have to use an original. Half the price of the Jag one, ordered Monday and it was delivered 1st thing next day. Only one problem the cable on the new one was 100mm shorter than the old one, but no problem as it still reached.

Well the big question is did it work? Yes all fitted in under 5 minutes and yes gone is the P 1647 fault code.

However the 4 injector codes still remain which is a bit of a bummer and RP
Is still being triggered on the 2nd cycle. However the system is now going into closed loop and I am getting assorted readings on the ST and LT fuel trims.

The engine is still running and performing extremely smoothly so what ever can be causing this?

At least I have got rid of one of the fault codes!

 

Let's have the STFT and LTFTs then!

 

It seems that many moons have risen and set since we first tried to look at the fuel trims.

I presume that I need to look at STFT% 1&2 and LTFT% 1 &2. I can't remember am I supposed to check all 4 at tick over and then at 2500rpm? Should they remain stable and be equal?

There seem to be a load of other FT readings such as fuel trim bank 1 sensor 2 and fuel trim bank 2 sensor 2, I presume I don't need these?

 

Did the test at tick over and then 2500rpm

I started the engine Luke warm and at tick over both stft 1&2 went up to 15% initially then quickly dropped to between 0 & 5%. On leaving the engine ticking over they both fluctuated between very slightly above and below 0%.

On revving to 2500rpm again both the STFT went up to 8% then dropped to 5%. They then further settled to between 5% & 0%.

At tick over ltft1 started at 0% then went to 5% then settled between 3 & 4%. Ltft 2 started at minus 2% then went up to 5% then settled back between 1 & 2%

At 2500rpm both ltft 1 & 2 start at 5% then settle to 8%.

Hope you can make something from all this!

I can't remember the cylinder layout on a v8, in what way are cyls 2, 3, 5 & 8 linked, there must be some common denominator that is causing these injector faults to be all listed together? Ignition module 1 is for cylinders 1, 4, 6 and 7 and ignition module 2 is for 2, 3, 5 and 8, but how would that be linked to the injector circuits?

 

Before you get too deep in this, go to this thread and read my two papers on fuel trims. They will help you get a grip on trims so you will have a better idea what you are looking at, and why.

https://www.jaguarforums.com/forum/g...ed-quiz-49317/

Cheers,

 

I think you must be looking at a wiring fault. I assume you've cleared the codes and seen them come back?
Clearly the injectors are working so there's something the ECM doesn't like.
You can unplug the harness from the ECM and check the resistance of each injector between the ECM end of the harness and Pin 5 of the injector relay to see if they're all the same (not sure bur 13 ohms comes to mind).
It won't hurt to swap the injector relay but you'd think that would banjax all the injectors.