It's on again...

[J44EAG]

Sounds like a real persistent fault which Ray should be able to diagnose with his dealer level kit. If he can obtain the fault code this will then give him a pointer towards the issue. Then you will be getting somewhere.

Mike

[RichardSEL]

<snip>
If you need new cats, talk to Longlife exhausts in Carshalton, Surrey. Costs for internal media parts may be a lot cheaper than you think when compared to genuine units. See my "Let it flow" article in X350 pages of last months magazine. If sensors are needed then I believe it is worth approaching Gendon as a possible supplier.

Spoke with Longlife and they do not rebuild cats but build bespoke SS exhaust systems only. They didn't know the XJ8 3.2L insisting it was a V6...

They don't have sensors to hand -- if they are needed they buy them in from Jaguar (wouldn't want to have a new exhaust system with the old sensors in it )

[RichardSEL]

Sounds like a real persistent fault which Ray should be able to diagnose with his dealer level kit. If he can obtain the fault code this will then give him a pointer towards the issue. Then you will be getting somewhere. Mike

Doesn't say what kit was connected when I had the codes cleared. Diagnostic report just gives:
(car details)
Vehicle Software Version V19.11
Diagnostic Application Version: 3.05.021
Test Time: 2016-09-14 13:41:11
Diagnostic path: Manually Select>XJ TYPE>2001
Diagnostic Result
P0420 Catalyst system efficiency below threshold (bank1)

Which is what Longlife say only their scanner would tell.

[ptjs1]

Richard,

As you probably know, the car doesn't really know if the cat is working properly or not. All it can do is compare the voltage traces on the pre-and post-cat lambda sensors and draw a conclusion. So a P0420 is merely an internal conflict between the voltage readings which is then interpreted as the cat must not be working properly. Yes, you might have a shot cat, but it would be naive to assume that just on the fault code. I would bet that for every 1000 times a P0420 code has been thrown, it's only once that a cat has been shot. You can get a P0420 code thrown through conflicting failing lambda sensors.

This is why proper diagnosis is really critical or owners end up throwing money at parts that don't cure the problem.

AFAIK, The car can't throw a P0420 without the engine being run so it might be that the car is still holding another residual EML fault, (you may now have a different fault code from when it was first scanned)

I'm just guessing but I would assume that Ray will interrogate any existing codes, erase all codes, run the car then see what happens and start his diagnosis. For example, monitoring the lambda voltage readings and overlaying that with the emissions readings can start to give a clue.

Good luck

Paul

[RichardSEL]

Only Called Longlife to get some ball park idea of costs should Ray diagnose cat failure -- but at 121k, post and pre-cat sensors are also real possibilities.

Given that I've done the hard resets, and the EML still comes up at IGN on without engine run, am assuming the pre-run diagnostics are doing a DC check on the sensors and that fails so throwing a fresh EML. As you say, if indeed those sensors are the fault.

Of course, will wait for diagnostic before jumping in. But it's such a nice drive...
So's a Citroen DS23 Pallas

I've got the OBDii diagnostics for VAG group cars, but don't think that program would give any indication (VAG-Com aka VCDS by Ross Tech)

Where's the OBD port? Just in case I spot an AA/RAC van close by that could do a quick check...

[ptjs1]

Richard,

OBDII port is on under dash kick panel just to left of steering column. Be very careful when you connect your OBDII plug. The x308 mount is prone to coming loose, wires are tight and can get chafed and really mess things up. (Don't ask me how I know this!!)

If you've got an OBDII plugin, any of the readily available software will enable you to monitor lambda voltage. I just use the Torque Pro app on my mobile phone which cost the princely sum of £1.69.

I wouldn't worry about any lights that are on with just ignition on. It's only if they continue when the engine is running.

Cheers

Paul

[RichardSEL]

Richard, OBDII port is on under dash kick panel just to left of steering column. Be very careful when you connect your OBDII plug. The x308 mount is prone to coming loose, wires are tight and can get chafed and really mess things up. (Don't ask me how I know this!!)

Still leery about using my VAG-Com there. Their support forum has had a few reports over the years of some marques other than VAG group giving a report but being read only. Hughie Ross of Ross Tech (the original writer/inventor) says he doesn't like his kit being able to do others outside of VAG. Mind you (as an aside) he had to change the name Vag-Com to VCDS because the vast Volkswagen Audi Group didn't like him using those three letters and threatened all sorts of Armageddon if he didn't stop.

If you've got an OBDII plugin, any of the readily available software will enable you to monitor lambda voltage. I just use the Torque Pro app on my mobile phone which cost the princely sum of £1.69.

I'll just have to be patient until next week. A DS23's not so bad. Once you get used to it

I wouldn't worry about any lights that are on with just ignition on. It's only if they continue when the engine is running.

The EML does stay on when running. But the trip into Kent on Sunday A20/M20 and countryside down to Challock didn't give any discernable difference in performance -- apart from a little lower MPG. But the stored average counter was starting from zero

[RichardSEL]

The story so far...

Our intrepid bargain hunter found a '01MY XJ8 3.2L with 120k up ("you might have to do that wheel bearing, mate") cheeep but glistening.
After replacing the not so attractive Apollo 18" rims for the more appealing 17" Celtics, a water pump, coolant flush thru and replace plus a dollop of k-Seal to ensure no exhaust gases getting into the water jacket, and a new battery; a persistent EML showed up "P0420 Catalyst system efficiency below threshold (bank1)" which was cleared by scanner but only to return a hundred miles or so later. The EML could not be cleared by a hard reset of overnight battery disconnect

Now read on...

Ray of Surrey Jags performed a check for presence of gases in the coolant and found none. Test fluid stayed bright meths blue
Then found pebbles jammed in the suspension between rear A frame and NS spring cups or lowest coil leading to an intermittent "Creak!" sound exactly like a wheel bearing would.
Found shocks were OEM on the front and a bit wet, found an OEM and an odd Munroe for rears.

Hand scanner read and cleared EML which was the same as previous P0420 Catalyst. Had already consumed two courses of CataClean each per 15L of fuel so waiting to see whether EML returns.
Apparently this EML is not one that's capable of being extinguished by a battery-off "hard reset." So must write itself into NVRam some wheres? Replacement OEM Cat unit ~£800 inc for OEM. EML stayed off on return journey back

mf (hope not )

[J44EAG]

Replacement OEM cat prices were why I pointed you originally towards Longlife Exhausts. OEM prices are just crazy.

Longlife do indeed build part or full bespoke exhausts. This includes fitting less restrictive 200 cell cats at prices that are much lower than OE components. The retail price for gutting out a pair of old cats from my car, fitting 2x 200 cell replacements and building the special low restriction X-pipe arrangement on my car was £930. I paid rather less than that. So for the cost of just one OEM priced cat, I got two faster cats and the X-pipe!

So if you do eventually find you need exhaust components, it is well worth consulting Longlife to see if they can save you money and give you a really decent exhaust to boot.

Stones on the rear damper/spring mounts are not an unknown problem. Seen that several times.

Mike

[RichardSEL]

Read your excellent article, Mike. Guess I just happened to speak to someone on the 'phone who "didn't know" <----euphemism
I'll take it down there if I have the EML again. And PM you for someone you know that I can make an appointment with?

Ray added that at 121k the same EML's likely to return especially at higher revs.

BTW, is an '01MY XJ 4L Sovereign LWB still considered X308 build?

[J44EAG]

Dan Mattews is the MD, with Ellis as his engineer. I`d recommend a visit as on the phone these guys are always rushed and best results and deals are obtained standing face to face. With the car on the ramp, these guys are the business. Phone to make the appointment, then go from there.

Yes, the Sovereign at that age is definitely X308 and nothing else. The later 02> onwards X350 is a totally different beasty.

Mike

[ptjs1]

Richard,

Has no-one yet monitored the lambda voltage traces? As mentioned, your code is being thrown through a comparison of pre- and post-cat lambda voltage readings. Someone has to check those lambda sensors before you can conclude anything.

All XJ8s all the way up to 2003 are x308. If it's a 4 litre XJ8 it's a x308 as there's no x350 4 litre.

Paul

[RichardSEL]

Ray just opined that I should use Cataclean to see whether the EML stays off. I told him I'd already done that x2 and he said that the cat's probably gone, as it's not the sensors because they're giving the "too weak (bank 1)" fault. Which was the same fault as previously stored and cleared.
I don't know whether he did the Lamda traces to come to the conclusion that that cat had had it.

Just doing a comparison of the X308 Sovereign 4L as against the XJ8 3.2L. The 4L's 43k miles younger, it's a LWB, only three owners from new, and has all the toys bar sunroof. Did the Sovereign ever offer a dividing panel as an option? Or was that only Daimler?

The costs needing a spend are the same. But for some reason (mebe the V-Power?) the 3.2L feels more "sprightly".

[ptjs1]

Richard,

If you don't get round to checking the lambda voltages, you'll go round in circles and end up either selling the car or buying a new cat, neither of which might be necessary. So, I suggest you start with the voltage check. You hadn't replied as to whether you had an OBDII plugin although you've referred a few times to some sort of VW equipment. Most OBDII software provides basic compatibility with most cars so I would just try and check the voltages with that. If not, just buy yourself a plugin for less than £10 which will usually come with PC OBDII software. If not, just buy a cheap £2 mobile phone app to interface with the plugin and check it that way.

As regards, the 4 litre, it's more powerful and more frugal than the 3.2 and Sovereigns have many more toys. All other things being equal, a 3.2 or a 4.0 Sovereign? i know which one I'd buy! (In fact I did!)

Paul

[RichardSEL]

<snip>
If you've got an OBDII plugin, any of the readily available software will enable you to monitor lambda voltage. I just use the Torque Pro app on my mobile phone which cost the princely sum of £1.69. <snip>

Paul...
As you may have seen in my "Exhausts" sub-forum post just needing to get confirms that I've got to change both my Cats
as my i930 is giving the codes for both Bank 1 and Bank 2. So, as you point out, need to eliminate sensors' faults.
You mention above that any of the monitors will show lambda voltage. I've learned that I need to see fluctuating on the pre- and stable volts on post-cat sensors. But how can I see these on the i930 which is what I shelled out for? No Torque Pro app here as I've only got a sad 'phone. There's no sensors' fault being shown on the i930, just both Banks... which stays clear for a few hundred miles and returns irrespective of being driven hard or not (now)

Thanks for your insights
Richard