Wrinkly

never

when

Is

Aimlessly

Not damming Ebay or any other site at all, but do be aware of quality of the parts you are buying. A lot of cheaper, especially far eastern, manufactured parts are not up to O.E. specification, although warranty sounds OK, sometimes having to claim it can be difficult. If they happen not to last, you have the added expense of paying for the parts to be fitted again, if not having to buy new parts as well. I am definitely not saying "Do not buy them", but I am a firm believer in "You only get what you pay for." Best Wishes in correcting your problems. Regards, John

Minstrel

Sooty

tears

Still not able to find cause of P0420 code, despite all that has been done (as per above details in this topic). However the car has recently had, six of each, new Ignition Coils and Spark Plugs (all good manufacture, E.G. Denso) and Inlet gaskets were new ones of Jaguar origin. Is it possible that during re-fitting the Inlet Manifold, that a gasket has been pinched or not positioned correctly. The car is showing no signs of what is usually considered as typical Cat Converter in effective, E.G. Smell, low mpg. smoke, power loss etc. etc. Every time the code is read and reset it appears again in 18 -20 miles of use. Cannot seem to be able to link this to previous posts on my topic and problem, sorry. Am now desperately seeking further help/advice please. Further advice would really be appreciated. Regards and Best Wishes, John

smile

Manufacturer

Petrol and getting 24 - 26 mpg.

Could you not reset your trip miles indicator each time you put fuel in. You obviously have an idea what your mpg is and could judge your travel distance from the trip re-set. Good luck.

Money

Still not able to find cause of P0420 code, despite all that has been done (as per above details in this topic). However the car has recently had, six of each, new Ignition Coils and Spark Plugs (all good manufacture, E.G. Denso) and Inlet gaskets were new ones of Jaguar origin. Is it possible that during re-fitting the Inlet Manifold, that a gasket has been pinched or not positioned correctly. The car is showing no signs of what is usually considered as typical Cat Converter in effective, E.G. Smell, low mpg. smoke, power loss etc. etc. Every time the code is read and reset it appears again in 18 -20 miles of use. Further advice would really be appreciated. Regards and Best Wishes, John

Sticky

Sunken

Destruction

finish

Humour

As in starting a car, especially an S Type, if battery is low.

Jim Have removed airbox as your suggestion, no obvious air leaks. I am assuming it is in order to lightly hear air passing along from the air cleaner when I have my ear on the delivery tube to the throttle body. Regards and Best Wishes , John.

Jim Thank you very much. I will attempt to look into this. Regards and Best Wishes , John

Have been doing a bit of searching around the internet and have found this entry on a USA Jaguar website, concerning P0420. It is suggesting that most of these codes P0420 generated are due to air intake via leaks, on usually plastic joints, is causing the problems. Leaks via Inlet Manifold etc, etc. and is shown on a video link in the posting. I would really be grateful if some of the well informed members of this Forum would be kind enough to view this link and video and give me there thoughts/opinions on the suggestion of too much air being read by the Lambda Sensors. As per my post above I just do not know where to go from here now that both Lambda have been replaced. https://www.jaguarforums.com/forum/x-type-x400-14/p0420-kept-coming-back-11218/page2/ Many thanks, Best Wishes and Regards, John.

Have posted before on this subject but am now at a loss as to what to do to correct. History of attempting to correct: Car was MOT`d April this year and had nothing needing attention and no points for attention. So, plainly must have had correct/acceptable emissions at that stage. Has done exactly 1845 miles since MOT. Car was serviced and I mean full service 1494 miles ago. 800 miles ago the Ignition Coils 6, Spark Plugs 6, Inlet Manifold Gaskets 6, were replaced because of a faulty Ignition Coil on Cylinder No: 3. Less than 300 miles ago Yellow Engine Management Light appeared. OBD11 code Reading P0420 Catalyst System Efficiency Below Threshold. Bank 1. (Left Bank when stood looking at engine from front of car. Correct I believe ?????). Upon advice the Lambda Sensor Upstream was replaced (Denso as OE.). after only 20 miles the same fault kicked in again. The Lambda Sensor Downstream (again Denso as OE) was then replaced. After18 miles today the same fault has appeared I.E P0420, as above. 1/ Would appreciate advice on what to do next to correct this fault. 2/ Has anyone any experience of using branded Catalyst Cleaners that are put in the fuel tank and run through the system. The advertising for them, as one would expect, is full of praise and "a cure all". Is it worth trying for the sake of £20. Will they cause any harm or damage. 3/ Do you believe I am really looking at the costly action of buying replacement Catalytic Converter/s which seem to be in the region of £155.00 each. 4/ Due to travel to Cornwall in two weeks and would like to correct this before the weekend away. 5/ Will it do any damage to run the car with this fault not corrected and the Yellow Management light continuing to show. In anticipation of receiving some advice on above questions I would thank you in advance for your time and efforts on this problem Best Wishes and Regards, John