Hi all.
I've been struggling with trying to solve my P0430 fault code in my car. Engine bay light is on. I took it to my local garage, who did an emissions test, which it passed, except it did have an high CO reading:

This was Natural Test:
CO: Limit - <=0.300%. Actual value -0.299%

But on fast idle test:
CO: Limit - <=0.200%. Actual value - 0.066%

So trying to work out if it still could be the cat failing.

Any ideas please?

Many thanks, Paul (In the UK)

S Type, 2001 (Y Reg) V6, Manual, Petrol

 

Have a read of this Paul and especially the last post which is about how a cat becomes more efficient the hotter it gets. That exact scenario has been shown during your garage CO test where the higher the revs are the hotter the cat is the more efficient it gets and the % of CO that you are seeing is less.

https://www.jaguarforums.com/forum/s...t=English+2001

Also read Brutals posts, he's the man.

 

Hey MrPaul,

I think you will want to take a look at this thread too: https://www.jaguarforums.com/forum/s...ad.php?t=32784

I was having the P0420 code, which if I remember correctly is just the other side. Mine P0420 was the passenger side (on the 3.0L). I am pretty certain the P0430 is the driver side.

I changed out all the coils and plugs hoping it would solve the problem. It did not, but the car ran more smoothly. The coil packs in it had about 85k miles when I changed them. The replacements cost me about $150 for the set IIRC on eBay.

I was still getting the CAT code though... Then I tried the Lucas... and I am running 89 octane with no CEL/P0420 for six tanks now...

We do not have an emissions test here, but the engine is running smoother than ever and the computer is happy with the current situation! I am also very happy with the 20% increase in MPG and the additional savings by not having to run 93 octane gives too!

 

A failed cat won't pass emissions but a failing cat might. If something's making it fail you need to stop it getting worse.

You can:
change parts and hope
run cleaner through and hope
diagnose using OBD
get a tech to diagnose the system.

The tech's the best but may be costly. OBD will give you info to decide what to do. The others will work but you may throw unnecessary $$$.

 

If you read a bit on what that code means, you will find it can be a lot of things. That is why I did not start with changing out the CATs. Your reading was within limits (even if just barely at low RPM).

Some of the things the P0430 code can be caused by are unburned fuel making out of a cylinder, too much oil making it into the cylinder and not burning, etc. etc.

A lot of things can cause those problems: piston ring beginning to fail, an exhaust valve failing or not seating properly, intake valve not sealing properly, an injector pumping too much fuel or not misting it well enough, lots of things.

When I was getting the P0420 codes the OBD always said it was happening at higher RPMs, usually under load. Since your CO reading is worse at low RPMs it might be something different... But I would try the Lucas before you spend too much money elsewhere. (Just me...) I tried lots of other products and this one is cheap and seems to work.

The other thing is that high octane fuel burns more slowly. So I swithced to 89 octane since one of the potential causes if simply unburned fuel getting into the exhuast. I do not hear any detonation or other engine issues with the lower octane fuel and no new OBD codes popping up. (That may not be for everyone, but my Jag has 105k miles on it now... I figure I will likely only get another 70-100k, 2-3 years, before it needs a ring job at least. It had about 82-85k when the CAT codes started popping. Just outside of the 80K warranty here in the USA. You might want to check what the warranty is there in the UK and see if they wil replace them.)

 

Many thanks for all the replies, you are all too kind

Here is the full emission reading:
Sheet 1

Engine temp measurement by manual observation of cooling fan, Engine speed measurement was by-passed

Fast Idle Test

Engine Speed: Limit - 2500-3000 rpm. Actual value - Manual check = Pass
CO: Limit - <=0.200%. Actual value - 0.066% = Pass
HC: Limit - <=200ppm. Actual value -2ppm = Pass
Lambda: Limit- 0.970-1.030. Actual value -1.008 =Pass

Natural Test:

Engine Speed: Limit - 450-1500rpm. Actual value - Manual check = Pass
CO: Limit - <=0.300%. Actual value -0.292%

Overall result: Exhaust Emissions test = Passed

Sheet 2

Engine temp measurement by manual observation of cooling fan, Engine speed measurement was by-passed

Fast Idle Test

Engine Speed: Limit - 2500-3000 rpm. Actual value - Manual check = Pass
CO: Limit - <=0.200%. Actual value - 0.038% = Pass
HC: Limit - <=200ppm. Actual value -6ppm = Pass
Lambda: Limit- 0.970-1.030. Actual value -1.008 =Pass

Natural Test:

Engine Speed: Limit - 450-1500rpm. Actual value - Manual check = Pass
CO: Limit - <=0.300%. Actual value -0.299%

Overall result: Exhaust Emissions test = Passed

---------------------------------------------------------------------

Looks like it could be so many things, but knowing my luck it'll be the cat failing.
It's in for an MOT tomorrow and another emission test will be done. I want to see if there are any other major problem with the car, because if it needs too much money to put right, I will have to look for another Jag.
I may just bite the bullet anf let the main dealer sort out the problem, as it can be costly repairing the cheaper things only to find out it was the cat all along.
I'm not sure what a lucas is? Because I'm in the UK, maybe it's called something else here.

A garaghe did look at the senor operating through a obd computer reader. All three were giving volts from 0.400v to 0.840v, but one (Bank 1 sensor 2) was only reading 0.055v to 0.115v. This is a downstream sensor I'm told on the drivers side. Was told bank 1 is drivers side, steering is on the right in uk of course, so maybe different in USA. But if that is causing problems why would I be getting P0430 which points to an error on Bank 2?

Many thanks, Paul

 

You may not have it. Lucas is the company. You can read more about the product I used here.

 

Hi MrPaul, from Leeds...Your CO (carbon monoxide) being too high means some of the fuel is incompletely burnt, i.e. it should be CO2 when completely burnt. If all other engine components are working properly, this means a rich mixture if the engine is at normal working temp. However, if under a cold start, the mixture WILL be rich esp. at idle to make the idle smooth, also to make the take-up smooth without flat-spots and hesitation. However, even when hot, the idle has to be rich (abt. 12:1) because of exhaust gas dilution of the inlet mixture. Remember both valves are open at once for a short time at idle too, this is how the dilution happens. (Something eliminated by variable valve timing).
That's why the CO reading at idle is greater. During mid-speed, mid-load, the mixture ratio is stoichiometric, abt. 15:1. This burns all the fuel leaving some excess air in the exhaust. The excess air or oxygen is sensed by the lamda sensor by altering the shape of the slow square wave (half a hertz or so) which can be read by the computer. The computer adjusts the fuel injection to produce a little free oxygen in the exhaust at mid revs., making hopefully for the good 15:1 ratio (least pollution, best fuel efficiency).
The upshot of all this is that just about anything could cause high CO at idle, but the lamda sensor itself is a common favorite culprit. It's not an elegant solution to rely on the catalytic convertor to burn off the CO to CO2, it's better to get the engine operation right first, say I. Best of luck with that one.
Leedsman.