Oxygen sensors replaced but still rough idle
#1
Oxygen sensors replaced but still rough idle
My 2001 XJR started to smell a little rich (to say the least) and I discovered two fault codes (P1646,P1647). I took it to my mechanic, who is very experienced on Jags from this era, who replaced all 4 oxygen sensors. Both fault codes were rectified. He said the sensors were black with soot - which he'd not seen before.
The car is running a little rough when idling (in any of PNDR), more so when it warms up I've noticed. My mechanic has said that it's not possible to reset the ECU on this particular year XJR so it will just need to learn and adjust. It's been three weeks now and it still has regular erratic idling.
Can it take this long (at least 200km driving motorways/city) for the ECU to retrain with the new sensors?
Obviously I'll get back in touch with my mechanic but just wanted to see if anyone had any sagely advice
BTW: I can monitor the sensors via my Torque app but am not really sure which to look at The app has 8 sensors, not all of them are showing activity, and each sensor has:
The car is running a little rough when idling (in any of PNDR), more so when it warms up I've noticed. My mechanic has said that it's not possible to reset the ECU on this particular year XJR so it will just need to learn and adjust. It's been three weeks now and it still has regular erratic idling.
Can it take this long (at least 200km driving motorways/city) for the ECU to retrain with the new sensors?
Obviously I'll get back in touch with my mechanic but just wanted to see if anyone had any sagely advice
BTW: I can monitor the sensors via my Torque app but am not really sure which to look at The app has 8 sensors, not all of them are showing activity, and each sensor has:
- Wide Range Current
- Voltage
- Wide Range Equivalence Ratio
- Wide Range Voltage
#5
Hi Vauxi, are you 100% sure about that? My mechanic used to work with Jaguar in the UK when these models were released - and he said that this particular year/version ECU it was not possible to reset.
#7
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#8
Oh, I see - these codes [put very very simply] mean pass or fail, but it has to be one or the other? I just use the Torque app with the OBD2 but my mechanic has said there are no fault codes showing when he scans it.
#9
you can flash program them with the right tools but the only day to day task you need is to pull the fuse/unplug battery to reset your trims.
#10
If the spark plugs are new and especially if they are iridium plugs, you may have a vacuum leak. Check the plastic hoses that go to the throttle body and the manifold under the throttle body. Also, check your oil cap gasket. High fuel trims will be a sign of vacuum leaking and these cars are very sensitive to this problem. Make sure the little hole under the plastic hose on the oil fill side valve cover is clear as well.
#11
One of my 2000 VDPs had a skip when idling at operating temp. The car would do this especially if in drive while stopped by the brakes. I did a lot of fooling around with no avail until I swapped all the coils from my other car and then the problem moved to the other car. Then I swapped coils until i located the faulty one and replaced it. When measuring the faulty coil with an ohm meter, it had similar readings to any other coil so I did not expect the coils were the problem. I also had a rough idle problem some time back that turned out to be a crack in one of the plugs.
Just a thought....
Just a thought....
#12
#13
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EscapedApe (04-05-2022)
#14
They're not fault codes (in this case) - any P1xxx code on any car is non-generic i.e. the car maker can have them mean absolutely anything (so you need to look them up in that car's info, which in this case you can download free from this site or JagRepair.com - Jaguar Repair Information Resource).
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EscapedApe (04-05-2022)
#15
Okay, so and update for anyone interested
After being away and too busy to get this looked at, I'm booked in to have it checked by my mechanic on Monday.
Worryingly, he made this comment:
I said something like, wouldn't be a big coincidence if a problem developed with the catalytic converters at the same time the oxygen sensors were replaced?
...hopefully it's something simple
After being away and too busy to get this looked at, I'm booked in to have it checked by my mechanic on Monday.
Worryingly, he made this comment:
Okay I think it’s the catalytic converters. Will run some tests and see what happens.
The reason I’m thinking cats as when the oxygen sensors die it can default to rich settings and possibly block a cat.
Last edited by EscapedApe; 07-01-2022 at 08:25 PM.
#16
I'm not 100% sure but my yo2000 xjr was possible to reset via ids. Sorry for delayed answer.
#18
Common issues include using the wrong sensor type or replacing the wrong one...