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P0420 Code Reading. Catalyst Efficiency.


Wrinkly
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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

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23 hours ago, Wrinkly said:

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

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.

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If you do have an air leak, which is very possibly the cause of your problem, then having a smoke test done will show where the leak is. Failing that, removing the airbox back to the throttle body and carefully checking the joints and pipes may show up a potential leak.

 

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On 9/20/2021 at 1:18 PM, Jimbov8 said:

If you do have an air leak, which is very possibly the cause of your problem, then having a smoke test done will show where the leak is. Failing that, removing the airbox back to the throttle body and carefully checking the joints and pipes may show up a potential leak.

 

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.

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On 9/22/2021 at 11:25 AM, Wrinkly said:

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.

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

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  • 1 month later...
34 minutes ago, Vladster said:

John did you ever manage to solve this problem....I'm having similar issues.

Martin

In a nut shell NO. Still working on it but I will get to the bottom of it. I shall tell the world what the problem was once I have solved the puzzle. Have just invested in a full blown Jaguar diagnostic and computer, the IDS/SDD that Jaguar agents use. Am now in the process of attempting to learn how to use it. It does not seem very easy or straight forward. However for a 71 years young non computer brained petrol head, it was never going to be easy. I now have my son in law on the trail of of exploring the route to using it correctly and he is a bit of a computer technic who usually has success with sorting any computer that I manage to almost destroy. The other problem is I am not engineering competent on todays electronic mechanics as I was brought up on, in my early years of mechanics, on a Mk 2 Jaguar with no fancy electronics.  

The most advanced I ever maintained  were my Nissan 200SX`s and my Nissan Skyline.

Good luck with P0420 and please let me know if you find a resolve before I do.

Nest Wishes and Regards, John

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  • 2 weeks later...

I have decided to "take the bull by the horns" and invest in a new Catalytic Converter. None of the other suggestions/new parts fittings have made any difference to the P0420 code.

Fingers crossed that this will cure the code from keeping reoccurring. I will update as soon as the job has been done and tested for what is usually 18 - 20 miles, after resetting the code.

Regards and Best Wishes to Everyone , John

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On 11/7/2021 at 4:52 PM, Wrinkly said:

I have decided to "take the bull by the horns" and invest in a new Catalytic Converter. None of the other suggestions/new parts fittings have made any difference to the P0420 code.

Fingers crossed that this will cure the code from keeping reoccurring. I will update as soon as the job has been done and tested for what is usually 18 - 20 miles, after resetting the code.

Regards and Best Wishes to Everyone , John

New Catalytic Converter fitted yesterday. Quite a lot of destroyed rubbish found in the old one. (Photo attached). Code reset and has so far completed sixteen miles and no yellow management light as yet. On previous times of resetting the code it has taken up to 18-20 miles to regenerate. Fingers crossed this time. The moral of this story may be, I should not have spent time and money attempting to deal with the P0420 Code by cheaper methods first. I.E. new sensors upstream and down stream, smoke testing, checking all joints etc etc. Followed lots of sound and helpful advice but eventually had to "bite the bullet" and buy the new Catalytic Converter. Not to worry, hopefully job done now.

 

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