P1646 - out of options
 

Hello

my 02 XKR has been giving me the P1646 error code

According to this thread ( https://www.jaguarforums.com/forum/x...nfusion-57005/ ) this error code means fuel pump 2 relay failure for my model, year and vin number. (XKR, 2002, A 27989)

After testing the fuel pump 2 it turned out that the pump was not working but the relay is fine. I replaced the fuel pump and tested it, the pump now runs when the key is in the on position for a few seconds, it also runs when I do a kick down, big difference here.

However, after I clear the error code the engine light will go off but come back on the next time I start it. Each time after I reset the error code it comes back after starting the car. Any idea of what could cause this?

Regards, Mark

Was that multiple typos for P1646 rather than P1645?

sorry, just 1646, fixed the typo

I'm not sure where you are finding the code information, but for a XKR that's failure of the upper o2 sensor on the right (passenger side).

You can download the electrical guide, DTC (codes) summary and much more from jagrepair.com.

+1 bank 1, sensor 1

It comes back on every time because you haven't resolved the cause (see right hand column):

https://www.jaguarforums.com/forum/a...ions-p1646.jpg
As posted above, it's an HO2S fault and not fuel pump relay fault.

Graham

Hmm, I was going by this info post in the P1646 confusion thread

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

and this one

https://www.jaguarforums.com/forum/a...6-eng-mgmt.jpg

Next I will test the HO2S

Thanks

You can start by swapping the heater relays. They are the same, left and right. After swapping, if, after a reset, the error changes (to 1647 I believe), then you know a cheap relay is the fix. If not, then chances are the sensor is the problem. If it is, it is just a matter of ordering the right sensor (wide-band, not narrow-band) and swapping it out. A crows-foot O2 sensor wrench is your friend, here. Easy job if there is no corrosion involved.

Best of luck, keep us posted.

Thanks fmertz, I did that today and it turns out that the right upper sensor seems to be the culprit. It was quite a struggle to get it out and afterwards I read here on the forum that there is an AC plug or something where you can change the upper sensors from inside the car. Reminded me of the Citroen DS which has a plug in the dashboard to remove a hidden spark plug.
Anyways. putting it back together should be much faster now with the knowledge of the secret plug.

I'm a bit doubtful as to whether that's correct. It may have been OK at the date issued but in the later JTIS it looks to be that P1646 is always an O2 sensor fault.

At the least be doubtful. Maybe they changed the software so it is indeed always an O2 fault - that would mean unless a car was in the original range (if it ever was correct) and didn't get revised software.

However, xjrguy is pretty sure so I'd go with his view if in the range he mentions - or try both as possible causes.

My vin starts with A13 and the P1646 was given by the upper O2 sensor....

Hi there,

I have a crossover year XKR (2001 UK and 2002 US) that had the same symptoms last year... p1646 code showing. DTS said secondary fuel pump relay, but it was the bank 1 upstream O2 sensor.

One useful trick is if you have a cheap OBD reader. If its the O2 sensors at fault, the ECU won't go into closed loop mode so you'll have no fuel trims available on your OBD reader.

HTH