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[MaxV6]

okay, I know there's a fix involving moving the sensors....   but can someone educate me as to the underlying cause, and the prognosis....   

is it also fixable in the long term or medium term , by replacing the sensors?  or is it more about new Cats? 


roughly how long can one sensibly use the vehicle with the EML on as a result of these codes?  what effect does it have on the engine management , and so on.... ?



(yes we checked the memory and these codes were present when i bought it....  so it's not much of a surprise...   that  the EML is now on...  frankly  i suspect the seller had tech 2 reset it just prior to the purchase , in the hope we would be unaware.....   my ebay feedback deliberately did not include the word Honest!   )

[Jimbob]

its the precats that the monitor, and these do lose effiency over time / use  (and I suspect fuel quality too)

I dont beleive there are any real effects, maybe a little underfueling, not quite sure.

the 'real' fix would be to replace the precats, only about £600 each

moving the sensors works well.

be interested to know if a bottle of cataclean would help.

[aaronjb]

its the precats that the monitor, and these do lose effiency over time / use  (and I suspect fuel quality too)

I dont beleive there are any real effects, maybe a little underfueling, not quite sure.

the 'real' fix would be to replace the precats, only about £600 each

moving the sensors works well.

be interested to know if a bottle of cataclean would help.

Presuming the Omega works the same as other OBD-II cars, the post-CAT sensors are only used to check the efficiency of the CATs, while the pre-CAT sensors are used to adjust fuelling..

So the only downside is a pesky annoying light that might obscure an otherwise worse (or catastrophic) fault..

[Kevin Wood]

Presuming the Omega works the same as other OBD-II cars, the post-CAT sensors are only used to check the efficiency of the CATs, while the pre-CAT sensors are used to adjust fuelling..

So the only downside is a pesky annoying light that might obscure an otherwise worse (or catastrophic) fault..

Yep, Exactly right.

The only function of the post-cat lambda sensors is to monitor the cat efficiency. There is no effect on fuelling or engine operation at all and the only side-effect is having a pesky orange light glaring at you (and the fact that it's on potentially masking more serious faults).

It won't ever get bad enough to fail an MOT emissions test because under testing conditions the main cats are working so no point in changing cats.

Relocating the post-cat lambda sensors after the main cats will effect a permanent cure. I have another idea for an easier cure but am yet to test it.

Kevin

[serek]

Presuming the Omega works the same as other OBD-II cars, the post-CAT sensors are only used to check the efficiency of the CATs, while the pre-CAT sensors are used to adjust fuelling..

So the only downside is a pesky annoying light that might obscure an otherwise worse (or catastrophic) fault..

Yep, Exactly right.

The only function of the post-cat lambda sensors is to monitor the cat efficiency. There is no effect on fuelling or engine operation at all and the only side-effect is having a pesky orange light glaring at you (and the fact that it's on potentially masking more serious faults).

It won't ever get bad enough to fail an MOT emissions test because under testing conditions the main cats are working so no point in changing cats.

Relocating the post-cat lambda sensors after the main cats will effect a permanent cure. I have another idea for an easier cure but am yet to test it.
Kevin

you welcome to test on my car

[pscocoa]

okay, I know there's a fix involving moving the sensors....   but can someone educate me as to the underlying cause, and the prognosis....   

is it also fixable in the long term or medium term , by replacing the sensors?  or is it more about new Cats? 


roughly how long can one sensibly use the vehicle with the EML on as a result of these codes?  what effect does it have on the engine management , and so on.... ?



(yes we checked the memory and these codes were present when i bought it....  so it's not much of a surprise...   that  the EML is now on...  frankly  i suspect the seller had tech 2 reset it just prior to the purchase , in the hope we would be unaware.....   my ebay feedback deliberately did not include the word Honest!   )

You will find that others who experience this issue just reset the code when it happens providing it is not reappearing immediately. I have a cheap code reader to reset and problem arises every 6 months or so.

I think Entwood may come on and give his theory about fuel changes which certainly coincides with times that my EML has come on. I don't worry about it like a couple of other intermittent issues - have had them for years (with the car as well!!)

[Entwood]

okay, I know there's a fix involving moving the sensors....   but can someone educate me as to the underlying cause, and the prognosis....   

is it also fixable in the long term or medium term , by replacing the sensors?  or is it more about new Cats? 


roughly how long can one sensibly use the vehicle with the EML on as a result of these codes?  what effect does it have on the engine management , and so on.... ?



(yes we checked the memory and these codes were present when i bought it....  so it's not much of a surprise...   that  the EML is now on...  frankly  i suspect the seller had tech 2 reset it just prior to the purchase , in the hope we would be unaware.....   my ebay feedback deliberately did not include the word Honest!   )

You will find that others who experience this issue just reset the code when it happens providing it is not reappearing immediately. I have a cheap code reader to reset and problem arises every 6 months or so.

I think Entwood may come on and give his theory about fuel changes which certainly coincides with times that my EML has come on. I don't worry about it like a couple of other intermittent issues - have had them for years (with the car as well!!)

At your request good Sir ..

Basically .. I get the 0420/0430 codes twice a year .. 2 days after arriving in France, and then again 2 days after returning home. I carry a code resetter and it takes less than a minute to check the cause of the EML and then reset it.

I run on LPG and the "mix" of propane/butane in autogas varies from country to country ... the warmer it is the more butane in the mix.

My theory is ... the sensors get "used" to (or the system "learns") a set ratio of chemicals in the exhaust, and different fuel changes those parameters, if the change is big enough for long enough, on comes the light. Reset all the codes and it "learns" the new parameters until the fuel changes again.

I think it is more sensitive to LPG changes than petrol changes which is why those of us running the 3.2 on LPG seem to get the problem more than those on petrol. I use the same LPG supplier 95% of the time in the UK and I'm guessing their "mix" is pretty constant .. so no problems.

Before the LPG conversion, the only time the problem occured was after picking up some decidedly old and dodgy petrol in the "back of beyond"

The fact that not all 3.2/2.6 owners get the problem seems to indicate that the POTENTIAL for all to get it is there.. but SOMETHING triggers it more on some than others .. and my bet is fuel composition/quality.

Just my thoughts .. nowt else...   

[Dave C]

I agree with Entwood above that fuel quality has an issue whether or not the EML light comes on. I just fuelled up at the start of the month and after a few days the EML light appeared. No surprise to me as the fuel was from Tesco's. I have had this problem before with the fuel from these types of garages. Thankfully the last time i got fuel from a "proper" garage the EML light reset it self after a period of time and went out, so expecting it to reset itself this time.
I have also used Cataclean prior to an MOT and it seemed to work for me, but i know that this additive has a bit of a  contentious issue on this forum. 

Dave C

[aaronjb]

So out of idle curiosity I did the pedal trick before I left work tonight and lo, P0430

Must source myself some spark plug anti foulers..

[Kevin Wood]

So out of idle curiosity I did the pedal trick before I left work tonight and lo, P0430

Must source myself some spark plug anti foulers..

Already got some waiting to go on. Hold fire and I'll let you know if they work.

Kevin

[aaronjb]

I'm 'pretty' positive they'll work.. and you'll almost certainly get there before me, anyway  I really need to get the garage built..

[Kevin Wood]

I'm 'pretty' positive they'll work.. and you'll almost certainly get there before me, anyway  I really need to get the garage built..

I really need to get a new spring for my garage door so I can open the bu66er!

Kevin

[aaronjb]

Ditto.. when they moved the garage, the previous owners didn't put the door back together properly. If you let it slam shut then you need a crowbar to lever it back the 'right' side of the frame before you can get in 

[Marks DTM Calib]

I'm 'pretty' positive they'll work.. and you'll almost certainly get there before me, anyway  I really need to get the garage built..

Personaly I am not as I cant see how backing them off stops them from detecting oxygen (other than they will not be in the full flow so not nearly as hot). If they do work its probably because they are not hot enough to trigger.

But hey, lets hope 

[Kevin Wood]

Personaly I am not as I cant see how backing them off stops them from detecting oxygen (other than they will not be in the full flow so not nearly as hot). If they do work its probably because they are not hot enough to trigger.

But hey, lets hope 

I don't think it does. It delays their response by moving them out of the flow of exhaust gases. The ECU measures cat efficiency by timing how long a lean (or rich) condition takes to propagate from pre-cat to post-cat sensors as this is a measure of the amount of cat surface area that is still active and "storing" (then releasing) oxygen.

With the sensor inside a sleeve it takes longer for the gases to reach it but the sensor still remains active due to the internal heating so it's not flagged as dead by the ECU but also, with luck, it resolves the cat efficiency problem.

Only one way to find out for sure, though. I will hopefully get the chance to try them on my car later this week.

Kevin