Yep you never know what you will find untill you have a look see, didn't have chance to check out the relay yet so will still have to wait see, "TO BE CONTINUED"
regards

rrosscoe

 

If you have a coupe you can pull the pump through the subwoofer. See the post nearby for an explanation...

 

Hi Guys,
checked relay and physicaly it appears to be OK so will get a replacement and swop it out, mind you I suppose I could swop it out for one of the others just to see, will try. (hope I dont need to remove pump!)

Regards

rrosscoe

 

OK...so I have the P1646 code and a 4.0 non S/C 2002...where do I go from here?

 

Hi.

From JTIS Code P1646

VIN 001036-018108 no such code
VIN 018109-031303 Fuel pump 2
VIN 031304-A00083 Heated O2 sensor
VIN A00084-A11140 Heated O2 sensor
VIN A11141-A30645 Fuel pump 2
VIN A30646- and on Heated O2 sensor

My JTIS is only up to and including 2003 model year.
With your VIN, if the code indicates fuel pump 2 and you have no supercharger, there is an electronic ghost in your car as you have no fuel pump 2.
To the best of my knowledge.

 

P1646 : ECM H2OS control malfunction - 'A' Bank upstream

Default Action
ECM inhibits 'A' Bank upstream HO2S operation

Possible Causes
1. H2OS heater failure
2. H2OS sensing circuit short circuit to ground or high voltage
3. H2OS sensing circuit open circuit
4. ECM failure

If the vehicle is running, you can ignore possible cause 4.

Graham

 

Well this is just nuts.......
You think you have it figgered out and you find MORE conflicting tech information. I'm gonna work on this, but it's going to take a while.

Meantime, try disconnecting your Bank 2 upstream O2 sensor and running the car for a few minutes. Let's see if you set a P1647 for the other side. That might settle it for you; but I'm still going to try and find out why all the differences in the information.

Always sump'in, ain't it???

Cheers,

 

Given VIN is DA41C92NA25147...

It seems that...I have a "Ghost in the Machine". Drats.

A little more background. She runs fine, but for throwing the code.

Perhaps I have a hidden or ghostly SuperCharger?

 

Even more confusion... Ive been looking around for a while now and my head hurts...

Mine is an XK8 2002 VIN A242**... I'm quite sure I only have one fuel pump and so my P1464 has to be my car telling me that it wants to go home...

 

XJRGuy...

Forgive me, but how does one disconnect a "Bank 2 upstream O2 Sensor". And could you explain "set a P1647 for the other side"?

I will give these notes to my indie, as it is evident I am not as handy with my Jag as many are on this forum.

Thanks in advance.

 

Behind the engine, near the firewall, there is a bracket attached by two of the trans bellhousing bolts. Clipped to that bracket [or, supposed to be clipped to that bracket] are five electrical connectors. Four of them are squarish four wire connectors for all four oxygen sensors. [O2 sensors] The other one is wider and has about twelve wires, that's for the trans rotary switch. Two of the four wire connectors are gray and two are black. The gray ones are the two upstream O2 sensors. P1646 is for Bank 1 [RH side] and P1647 is for Bank 2 [LH side]. I was suggesting purposely trying to set a code for the LH side by disconnecting that one, clearing the codes and running it for a minute. Then check the codes again to see if the new code is induced.

You WILL have to clear the codes to do this because many times once the ECM sees a fault for an O2 sensor, it stops looking for others. It does that because it already knows it can't properly monitor the exhaust because of the first fault; therefore there is no reason to continue monitoring the sensors. Basically it disables the test in this case.

Good luck!

 

Forgive my "I dont get it itness". But does setting off the P1647 code prove that the P1646 is dead and all else is well?

Thanks in advance one again...and again...and again.

 

Dumb question I still don't know why I (my mechanic) wants to disconnect the O2 sensor.

Thanks in advance.

 

I think we need to re-group a bit here. Since this all started last year I have researched a bit on a couple of cars here. If you are still dealing with a P1646 code, we can stop messing with the O2 sensors. I've satisfied myself that the 2001-2003 XKR/XJR models set that fault when there is a fault with the 2nd fuel pump. Most notably because of a relay issue.

Where do you stand with your car right now, and why is he wanting to disconnect an O2 sensor??

Cheers,

 

XJRGuy,

I have a 2002 XK8 (non-S/C) 4.0...which does not have a second fuel pump. Hence my confusion.

The only reason I was wanting my indie to test the O2 sensor was from a prior string on this post.

Car runs fine with check engine light on throwing the 1646 code.

Thanks in advance.

 

I'm with you on the confusion.......geez, you'd think I should be able to read. My bad.

Anyway, now I'm not so sure that disconnecting the other O2 sensor will get us anywhere. I've come to the conclusion that will probably set a code more like P013x or P015x, and not a P1647. At this point, what I think really needs to be done is some pin back-probing at the ECM of the four circuits from each upstream O2 sensor. By doing that the technician can compare and look for something on the Bank 1 sensor that differs from the same circuit on the Bank 2 sensor. This will require someone experienced with circuit tracing, a good wiring diagram and some patience. This also means he'll need a little finesse, because the engine will need to be running.

So, I'd advise finding a good diagnostician, someone more than a parts changer, because something is obviously going on there. It just needs a competent detective.

Good luck!

 

Well, maybe I got an answer for you. Just got an XK8 NA AJ27 car in and did a test. It came in with an EVAP fault P0455 only. With the car running, I disconnected the Bank 1 Upstream connector, the gray one. Read the DTC's and had both P0455 and P1646. Reconnected Bank 1 and disconnected Bank 2. Read the codes again and still had only P0455 and P1646, never would set P1647.

As I explained some time back, [see post #31] once we record an O2 sensor fault, it generally STOPS LOOKING at the O2's because it knows something is out of whack.

So I cleared the codes and re-read them. [remember, I still have Bank 2 disconnected] After the re-read, there it is.......P1647. It went exactly as I mentioned before.

So there is an answer for YOU. [Someone with an XKR, not so much!] You have some kind of a circuit fault to the Bank 1 sensor, or a failed sensor. Now you need that detective.

One thing your guy could do is swap the two upstream sensors, clear the codes and drive until something resets. If it changes to P1647, you know it's the sensor, if it doesn't, you know it's wiring or [ouch], the ECM.

Happy hunting guy!

 

Steve,

Thank You!

Can my indie handle this or should I look for a diagnostician of (forgive me my indie) of a higher skill-set?

 

Wow, I hate to say it, but if your independent guy hasn't caught on by now, I think a [as you put it] higher skill set is definitely in order.

Good luck!

 

my head hurts,
Well my p1646 turned out to be the oxygen sensor and not the pump relay after all, I thought that mine was a 2001 model year according to the registration document but it turns out it is actually a 2000 model year after talking to my friendly jag dealership in Lincoln (UK) so as a lot of others i thought it would be pump relay but mine fell into the "up to 2000 model year range" and I was reading it as FROM 2000 mod year it is in fact the early coding and the expensive repair, I have had it replaced and the codes have cleared but I still have missfire on 7 and 8, tried swopping coils and plugs but still remains, when i removed the plugs and turned her over there was a lot of fuel blown out of the cylinders (7,8) so seems like overfuelling and fouling plugs, next check fuel trims if I can get into scanner to talk to it.
to be continued!
(2000 xkr)