XK8 / XKR ( X100 ) 1996 - 2006

P1646 Help

Old 06-12-2019, 02:37 PM
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Default P1646 Help

The last few weeks with this car have been very frustrating. Just when I thought I would be comfortable driving anywhere in the car I start having issues. I have recently started two other threads to help solve problems and am still working on them.

I started getting P1646 Code a couple of weeks ago. I ordered new O2 Sensor. Changed it out. Still have the Code. Checked Fuses (1 and 11) in the fuse box on Passengers Side (LHD). They were both good. Swapped Relays also on Passenger Side. No change still have the Code. So it looks like the ECM is next.

Is there a way to check before pulling?
If not what do I look for once it is out?
If I can prove it is bad is it better to have it rebuilt/repaired or buying used unit.
Anyone have suggestions about a rebuild or repair shop for ECM?

Thanks for any help offered.
Old 06-12-2019, 03:22 PM
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Bank 1 is passenger side.
Upstream is wide-band sensor.

Fuse 14 (10A) in ENGINE MANAGEMENT FUSE BOX seems involved too.
Old 06-12-2019, 08:09 PM
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Yes changed upper O2 Sensor on Passenger Side. Checked Fuse 14 and its good.
Old 06-16-2019, 04:00 PM
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Usually still getting the same code is:
1. wrong sensor make e.g. cheap
2. wrong sensor e.g. changed the wrong side / wrong position
3. wiring / connector / fuse fault

Seems almost never the module.
Old Yesterday, 04:31 PM
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Smile P1646 problem

Hi, I have a February 2001 XKR and have only just resolved my problem after many months of trials.
To cut a long story you may have replaced the Lambda sensor but not necessarily with the correct item.
Code P1646 signifies a fault on the STARBOARD bank upper sensor with the GREY connector.
I, like you, replaced mine with a new unit and the fault came back after the 2 start sequence.
After much research I found that the correct sensor has a resistance of 1.0 - 1.2 ohms whereas the new unit was 9.9 ohms and the defective unit was open circuit.
To confirm this I bought a used Jaguar unit from a Jaguar breakers for 17.50 and it immediately cured my problem and have now driven for 100ish miles without problems
Code P1647, the PORT side unit was also changed with a similar breakers part for 30.00 and that was also cured.
( This problem manifested itself when I asked a Jaguar agent to cure my P1646 but he changed the wrong side and also used a lower sensor by cutting theblack connector and splicing in the old grey connector, hence generating the new fault )
To change the Lambdas I found it easier to remove the Cat first as the bolts are easy to get at and a full joint kit cost me less than 10.00 per side.
Anyway I hope you have resolved your problems by now, but for anyone with a similar problem, please check your connector resistance for open circuit before embarking on full scale replacement.
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