The other day I changed out my O2 sensors all 4 of them.

Nothing wrong with original but I thought at 106,000 I should change them.

Soon after I got an error code indicating the forward sensors were malfunctioning.

So I swapped the original back in and now I get a lean bank 1 error code.

 

Might not be tightened up enough and allowing an air leak.

 

Did you use genuine Jag sensors or cheap ones? Generally speaking they don't randomly need replacing. It sounds like you were looking to fix something that wasn't broken.

 

I am hoping that is what it is and when the engine has cooled down will tighten the O2 sensors.

That is all I did, replaced the sensors, nothing else.

 

I used the recommended Denso sensors. Although I am now wondering whether I really got the correct ones?

Anyone know what the correct ones are for a 2005 XJR?

 

I know from experience that sometimes they do wear out at high mileage without giving up codes. Driveability was nearly night and day after I replaced mine.

 

According to Denso's parts catalogue the part # are:

A/F Ratio sensor(upstream ie front) 234-9030
Oxygen sensor (downstream ie rear) 234-4798

I have them on the shelf but have never installed them. Hopefully they are the correct ones!!

 

Those are the ones I purchased.

I have tightened both upstream and downstream sensors. About a 1/4 turn. I did use anti-seize compound on them originally.

Also while under there I checked the exhaust flange, on top of the cats, where I did manage to tighten one bolt a tad.

I do have 200 cel cats on this car.

Tomorrow I will take a test drive and Saturday I go on a 450 mile trip from MD to MA.

 

Drove about 15 miles just now with several pedal to the metal moments and no codes.

Before I was getting an error, after resetting, within 10 miles.

I will not be convinced of success until I have driven a lot further.

 

Thats a fact; Mine cleared a PO101 code, itself, then cleared the pending PO101 code for a couple hundred miles. Believed my issue was finally resolved as well. Was driving along and the darned thing came back on??? I too replaced four Denso oxy sensors, P C V valve, M A F sensor, with genuine Jag parts, as well as all ten intake manifold gaskets. Car runs great, and milage does get better as the parts are replaced. They just seem WAY TOO sensitive to me, guess should have replaced the M A P sensor, as well as the valley hose while i was there.

 

I have seen these issues too many times in this forum.

So as soon as I had the 2nd fault, lean on bank 1, I thought "oh no!".

I will be travelling 450 miles one way this weekend so will make sure I can clear the fault as often as possible.

At least I have replaced the valley hose: icon_lol:

 

I feel your pain

 

o2 sensors are indeed a 'wear item'. They are designed with a life (I shoot for 100k) and they are built to get richer as they get old (better to be too rich than too lean).
New sensors respond to the 02 readings much quicker, for better running and better fuel economy.

"genuine jaguar sensors?". No such thing, other than whatever brand jaguar used (denso, bosch, etc) originally...and they even change manufacturers as they go. You'll be paying a big price difference for that jaguar box.


If no exhaust leaks, the obvious culprit would be the high flow cats. You might need.

A few tips on o2 sensors:

*replace them all with the same brand. Different makers can have different return rates and cause CEL's.

*I usually just replace the front, main sensors if on a budget (or customer was). This is what the ecu uses to trim the fueling to keep it as close to stoichiometric as it can. The rear o2 sensors are used to read for a differential on the front reading to make sure that the cats are working.

That being said, jaguar does use the rear sensors to apparently tweak the air/fuel ratio even further, so again, replace like with like brand.

 

Well, I suppose when you open a can of worms, you should give up and go fishing !

 

Take a break, go fishing, but give up? Does not compute.

 

I will not give up but will go fishing in Buzzards Bay, Cape Cod next week!

 

458 mile nighttime trip from MD to MA with car heavily loaded. No codes.

My main worry was the heaviest load I have ever carried in the Jag. Since I had the back seats out ,because of replacing the headliner, I took the opportunity to load her up to the "gunwales" with dismantled Ikea cabinets and bins of books and papers.

I was surprised how well she handled with speeds ranging from stop and go to 100 mph with someone running interference ahead of me.

Even one hard braking episode thanks to a trucker suddenly pulling out in front of me on a two lane stretch.

 

That's the biggest problem with mine, runs so smoothly, as well as effortlessly down the road, with so much more power in reserve. Mileage in the high 20's, to low 30's when you can keep your foot away from the accelerator, on the highway, letting the cruse handle the throttle. What can be such an important issue, as to cause the idiot light to keep coming on?