Replaced 02 upstream sensor and still codes
#21
#22
Hey
Workshop manual, second edition (for 99-2002 cars) located in the second post in this thread: "WORKSHOP MANUALS - PDF Format"
https://www.jaguarforums.com/forum/x...ts-data-29800/
specifically
https://www.mediafire.com/file/ldfaeda4io2o16j
You'll find diagnostic procedures for the wiring faults in there under the relevant fault codes. Make sure you are looking at the procedure for the NA car. Be wary of the O2 sensor DTCs, depending on your cars year, because there are definitely mismatches between documented DTCs and the actual DTCs my car has thrown in the past. theres a series of tests to pinpoint where in the wiring you have problems when it comes to P1646.
good luck! In my case I just needed a new sensor, but it sounds like you may have a wiring harness fault. Maybe as simple as unplugging the ECU end of the harness, spraying with contact cleaner and re-connecting?
You will probably also need the electrical guide to identify the connectors, pins, wires etc. Also available in that thread.
Workshop manual, second edition (for 99-2002 cars) located in the second post in this thread: "WORKSHOP MANUALS - PDF Format"
https://www.jaguarforums.com/forum/x...ts-data-29800/
specifically
https://www.mediafire.com/file/ldfaeda4io2o16j
You'll find diagnostic procedures for the wiring faults in there under the relevant fault codes. Make sure you are looking at the procedure for the NA car. Be wary of the O2 sensor DTCs, depending on your cars year, because there are definitely mismatches between documented DTCs and the actual DTCs my car has thrown in the past. theres a series of tests to pinpoint where in the wiring you have problems when it comes to P1646.
good luck! In my case I just needed a new sensor, but it sounds like you may have a wiring harness fault. Maybe as simple as unplugging the ECU end of the harness, spraying with contact cleaner and re-connecting?
You will probably also need the electrical guide to identify the connectors, pins, wires etc. Also available in that thread.
#23
Hey just an update on my findings. I made a forum at a point explaining the issue and one person mentioned capacitors that could be related to the issue. Replaced all with brand new ones from Digi, didn't do anything other than fix the rough/irratic idle at times.
After
Before
I'm left with the fact that it may just be the sensors from RockAuto. Which all of them are denso 192400-3101. The one I pulled from the car that was bad had the same part number on it with of course a different date. Of course I wouldn't know if maybe it was changed to one that still didn't work via a old owner but who knows (192400-3101)....
In some forums I read some individuals stating the car depending on engine needs a specific sensor with a level of resistance which I'm not too sure on how true that is. But at this point any direction is welcome. I tested the wire harness and inspected it, no tears or burns or in the sock/grommet. ECM for sure now works at 100% no more malfunctions.
The only other test I can think of is swapping the connections for the two upstream sensors to see if the code changes via priming system check on the dash and allowing the code to represent itself.
For p1646 the current code it only appears (if cleared) after driving, no matter how long until you turn off and on again.
If anyone knows the correct part number if I'm wrong please provide it. I just want this code done and gone with.
At the moment IDS still isn't an option until my windows xp pro comes from eBay so I can run jlr 131v.
Car: Jaguar XK8 2001 Coupe 4.0L (LHD)
After
Before
I'm left with the fact that it may just be the sensors from RockAuto. Which all of them are denso 192400-3101. The one I pulled from the car that was bad had the same part number on it with of course a different date. Of course I wouldn't know if maybe it was changed to one that still didn't work via a old owner but who knows (192400-3101)....
In some forums I read some individuals stating the car depending on engine needs a specific sensor with a level of resistance which I'm not too sure on how true that is. But at this point any direction is welcome. I tested the wire harness and inspected it, no tears or burns or in the sock/grommet. ECM for sure now works at 100% no more malfunctions.
The only other test I can think of is swapping the connections for the two upstream sensors to see if the code changes via priming system check on the dash and allowing the code to represent itself.
For p1646 the current code it only appears (if cleared) after driving, no matter how long until you turn off and on again.
If anyone knows the correct part number if I'm wrong please provide it. I just want this code done and gone with.
At the moment IDS still isn't an option until my windows xp pro comes from eBay so I can run jlr 131v.
Car: Jaguar XK8 2001 Coupe 4.0L (LHD)
#24
Given you have tried everything else, that has to be worth trying to see if you can eliminate the wiring. It's hard to believe you have got multiple bad replacement sensors, but stranger things have happened. BTW good job on re capping the ECU
#25
#26
Another update, did some testing this morning and this what I found
-Test 1: I swapped both connections and started the car 3 times and let it idle from cold to warm
-Results: Received the same code p1646, after it was connected to the already working 02 sensor showing its not the sensor but wire harness.
-Test 2: I removed both connections, and I received p1646, p0031 and p0032
-Results: whilest I didn't receive 1647 the car recognized it wasn't connected to the 02 sensor on the left hand side of the car (bank 1)
At this point logically the only way forward is to completely check the harness leading to the ECM.
If anyone can provide a diagram in that case would be really helpful to further diagnose this weird issue.
-Test 1: I swapped both connections and started the car 3 times and let it idle from cold to warm
-Results: Received the same code p1646, after it was connected to the already working 02 sensor showing its not the sensor but wire harness.
-Test 2: I removed both connections, and I received p1646, p0031 and p0032
-Results: whilest I didn't receive 1647 the car recognized it wasn't connected to the 02 sensor on the left hand side of the car (bank 1)
At this point logically the only way forward is to completely check the harness leading to the ECM.
If anyone can provide a diagram in that case would be really helpful to further diagnose this weird issue.
Last edited by ocwolfy; 08-02-2024 at 03:41 PM.
#27
Just a thought, before going any further, are you sure P1646 refers to the O2 sensor on your specific car?
https://www.jaguarforums.com/forum/x...nfusion-57005/
https://www.jaguarforums.com/forum/x...nfusion-57005/
#28
Just a thought, before going any further, are you sure P1646 refers to the O2 sensor on your specific car?
https://www.jaguarforums.com/forum/x...nfusion-57005/
https://www.jaguarforums.com/forum/x...nfusion-57005/
Last edited by ocwolfy; 08-03-2024 at 01:14 PM.
#29
My car is a 4.0 XKR so definitely does have a second fuel pump relay. Having the same code number for different faults on the same base engine is beyond crazy. I can only assume it would be some kind of hangover from the early supercharged cars.
That post you quoted above, goes on to say:-
Maybe someone else can confirm this before you start soldering a new harness in place.
That post you quoted above, goes on to say:-
4.0L cars, SC/Non SC, P1646 = Fuel Pump 2 Fault
[of course, Non SC don't have a fuel pump 2]
4.2L and V6 Cars, P1646 = Heated O2 Sensor Fault
[of course, Non SC don't have a fuel pump 2]
4.2L and V6 Cars, P1646 = Heated O2 Sensor Fault
#30
My car is a 4.0 XKR so definitely does have a second fuel pump relay. Having the same code number for different faults on the same base engine is beyond crazy. I can only assume it would be some kind of hangover from the early supercharged cars.
That post you quoted above, goes on to say:-
Maybe someone else can confirm this before you start soldering a new harness in place.
That post you quoted above, goes on to say:-
Maybe someone else can confirm this before you start soldering a new harness in place.
And thanks for sharing this info! Definitely was new to me.
#31
Yes it is odd - the only reason I brought it up is because the DTC list for my car shows it as being for the fuel pump. Download the correct list for your model year car from Jagrepair (listed as Engine Management):-
JagRepair.com - Jaguar Repair Information Resource
You can check your model year from the VIN number.
Maybe this is just a red herring as we don't have the exact same car, but definitely worth double checking.
JagRepair.com - Jaguar Repair Information Resource
You can check your model year from the VIN number.
Maybe this is just a red herring as we don't have the exact same car, but definitely worth double checking.
Last edited by dibbit; 08-04-2024 at 05:39 AM.
#32
Thanks for all the help guys, after a very long thread I finally found the problem thanks to the workshop manual. After confirming p1646 did mean 02 sensor issues(open circuit) was for my car I went ahead and start checking the harness. The previous owner clapped the connections and it read high resistance. Here are pictures, I didn't notice it the first times as it was wrapped in electrical tape
As for my remedy I'm open to anyone educated in solving the high resistance. I'm about to do some research to correctly fix this bad job causing the open circuit
As for my remedy I'm open to anyone educated in solving the high resistance. I'm about to do some research to correctly fix this bad job causing the open circuit
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JagV8 (08-05-2024)
#37
You could switch the meter to volts and measure across the same two points with the ignition on to see if there's any voltage drop.
Does your meter properly read zero ohms when you short the probes together? I say that since mine shows around the same resistance in that state.
#38
0.7Ω isn't necessarily a high resistance. What two points were you measuring between?
You could switch the meter to volts and measure across the same two points with the ignition on to see if there's any voltage drop.
Does your meter properly read zero ohms when you short the probes together? I say that since mine shows around the same resistance in that state.
You could switch the meter to volts and measure across the same two points with the ignition on to see if there's any voltage drop.
Does your meter properly read zero ohms when you short the probes together? I say that since mine shows around the same resistance in that state.
My apologies, at first I thought it read in M when I recorded it when it was just ohm so disregard that update. ButI moved to another source possibly being the issue which was the grounding point. Yes( R) to R has good resistance. And Yellow was good as well so the harness checked out getting to the ECM.
So excluding the wire harness itself and the ECM I found that the ground was rusty and corroded. For EM1 within the (Main power disruption). After testing ground like the workshop manual sated the voltage was low and somewhat unreadable. I have one connection to the battery and tested the other prob to the wall of metal connecting to the ground as per procedure. I did this to some other ground points which tested fine.
Tomorrow I'm going to disconnect the battery and clean the ground points and inspect the cable just to be sure it's not damaged and see what happens from there.
Thanks for the correction.
#39
Just an update, after a long thread I finally located the problem, ground was the right track but wasn't necessarily the issue from the car itself though I did take the liberty of cleaning all the engine ground locations which weren't too bad
After getting to test E6, I found that the resistance was low for EM21 to ground being (44.8 Ohms) while my donor ECM which I am unable to code and use in the car tested 111.3 K resistance, passing the test for (is the resistance less than 10k ohms)
-Yes repair the short circuit
-No (replace the 02 sensor) and of course the 02 sensor is functioning as it should
In the picture is when I got to testing the spare ECM I had and it passing the test in the same car indicating the ECM issue.
(Located in the Jaguar Workshop Manual For year 1999 xk8.)
It looks like even after servicing the caps there was still a short somewhere in the ECM. Once it's found I'll provide some pictures. So it looks like that test where I unplugged the 02 sensor and the code not changing should have foreshadowed this. As the other side the code gave electrical malfunction to the 02 sensor rather than 1647 indicating a short or a short in the 02 sensor from being bad.
The more you know : /
After getting to test E6, I found that the resistance was low for EM21 to ground being (44.8 Ohms) while my donor ECM which I am unable to code and use in the car tested 111.3 K resistance, passing the test for (is the resistance less than 10k ohms)
-Yes repair the short circuit
-No (replace the 02 sensor) and of course the 02 sensor is functioning as it should
In the picture is when I got to testing the spare ECM I had and it passing the test in the same car indicating the ECM issue.
(Located in the Jaguar Workshop Manual For year 1999 xk8.)
It looks like even after servicing the caps there was still a short somewhere in the ECM. Once it's found I'll provide some pictures. So it looks like that test where I unplugged the 02 sensor and the code not changing should have foreshadowed this. As the other side the code gave electrical malfunction to the 02 sensor rather than 1647 indicating a short or a short in the 02 sensor from being bad.
The more you know : /
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