I'm having a little problem with my 2001 Jaguar XK8 convertible stander 400 engine. I just replaced the upper oxygen sensor on bank one and the car is now running a little rough but smooths out after it warms up. After driving about 10 or 15 miles and now get a 420 catalytic control error on bank 1 the same one I replace the oxygen sensor on. I have been a backyard mechanic for many many years but I don't have any of the sophisticated Electronics Equipment other than a little cheap code reader or any specially tools. I doubt very seriously that the catalytic converter is bad and I've read a bunch of descriptions describing the 420 errors and what the possible solutions for them. My question is since the new sensor was installed should I have also replaced the lower oxygen sensor on bank one? I really just don't wanna start replacing parts 'cause they're not exactly cheap and some of them are pretty hard physically to replace :-). I don't think Jaguars are noted for their plentiful room to work like a 1950s Chevy. I mean to replace the oxygen sensor your supposed to take off the entire exhaust system. Really!!!

 

This is were having a more advanced tool would pay. If you could read the fuel trims and sensor voltage you might know if the replacement was performing correctly. Did you use the correct Bosch sensor or a less expensive alternative?

 

Denso is also another quality Brand.

 

What he said ^^^, but also, a P0420 indicates the cat converter on that side is not performing up to snuff (at least that's what I've read), and it is thrown by the downstream O2 sensor (the lower one). There are products that claim to clean cat converters, then there's the possibility the O2 sensor itself could be bad. That can be tested if you have an OBDII reader that will show how the O2 sensors are performing.

 

thanks for responding , I bought the oxygen sensor from PartsGreek.com and it was $40. The oxygen sensor was : Autopart Premium Oxygen Sensor - Upstream
Part Number: 605-02675064
Brand: Autopart Premium
Notes: Oxygen Sensor
Detailed Notes: Upstream O2 Oxygen Sensor for Jaguar Vanden Plas XJ8 XJR XK8 1999-2003
Like I said before after I installed the new sensor the code has gone away and has now been replaced by the 420 code. My car has 111,000 miles on it.

When purchasing I did not see any Bosch sensors. I did search other sites and all I basically found was a whole lot of downstream sensors and very few upstream. Could you please tell me what advanced electronic tools I would need to fix this problem. I have a standard ohms meter and a $35 cheap code reader. I bought an expensive one and it wouldn't even see the car so I sent it back and bought a cheapy that at least gives me some coats. Appreciate any help I can get, Doug

 

I think you need to buy a Denso or Bosch sensor to get it working correctly.

 

I have learned to stick with genuine Denso sensors on these Jaguars. Anything else may cause trouble....

 

According to Denso site, correct up stream O2 sensor is 234-9016.. Now to shop with search engine and locate best price. $100-150 Ball park. Sent PM earlier. Buy from Denso suppler and it works. Most Jaguar electronics were Denso since Ford owned Jaguar . Alternators, starters and sensors I've found to to be Denso.

 

Thanks for all of your information. I just ordered a new Denso sensor I hopefully that will fix my problem. Thank you everyone am know a little smarter and a little poorer but if it runs smooth is well worth it. Thanks again for all your help and information, Doug

 

I just installed the Denso sensor and now everything is back to normal. Thanks again for all of your wisdom and willingness to share. Denso sensor are the only sensors I will be buying for my jag. Thanks again for all your help, Doug