help please P1646 fault code

[timberrel387]

Hi All

Pretty new to Jag ownership and picked up a 2002 XJ8 3.2 Sport with a few issues, one them being the P1646 fault code which i was told was the upper lambda sensor on Bank 1 of the engine (i think they are heated). the car drive ok with this code however i have changed it this week end and cleared the fault with my code reader.

drove it no problems no MIL light on, got in it today and the MIL light is back, hooked up my code reader and its back the P1646 code however on my reader its saying a Fuel pump relay no 2, confused as i thought this was only on 4.0 SC models, looked in the boot only to find i only have 4 of the 6 relays,

so i am now reaching out for help on this.

Thanks

Tim

[ptjs1]

Tim,

AFAIK, P1646 is definitely an o2 sensor code not a fuel pump relay. I'm not sure which code reader you're using?

The only I could think a relay might be at fault is there is perhaps a relay that controls the heater circuit on the o2 sensors, but then I would expect you to get a P1646 and maybe also a P1647 for both sensors not functioning correctly?

Hope that helps

Paul

[timberrel387]

Thank Paul

I have changed the 02 sensor on bank 1 which is what the local garage said, I am only using a cheap eBay code reader so that may be throwing up the problem

Just to be sure bank 1 is the drivers side on a U.K. car isn’t it?

Cheers

Tim

[Andy P]

Hi Tim.
Yes you are correct,+Bank 1 the right hand side of the engine when sitting in the car.
As regard to the P1646 Code the XJR uses the same code for their second fuel pump.
Just occasionally Jaguar have used a code for two different things (on different years of the same car or on different cars).
But the code you have relates to O2 Sensor on your car.
Now then,the question is have you bought the right one.
They do change regarding the year of car.
Here's a link to the correct ones for our cars:
https://parts.jaguarlandroverclassic.co ... nd/jaguar/
Hope that helps a bit and good luck.
Any other questions just ask away.Take Care.
Andy

[timberrel387]

Thanks guys

Looks like I will need to get another 02 sensor

Tim

[ptjs1]

Tim,

If you're able to, try just clearing the fault code, scanning again before starting the engine and clear again if necessary. Start the car and see if the fault code appears again. If it does, then try checking the wiring connections for the sensor plug. If all seem intact try checking the resistance reading across the wires for the sensor and tell us the reading. Also check for continuity for the black wire(I think?) being the heater feed wire, as this may be causing the problem.

Don't just throw another new sensor at the problem.

Good luck

Paul