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[computertel]

I posted a message a while ago saying I was having the emissions light coming on and on checking I found the codes 0420 and 0430 were flagging which indicate pre cat efficiency low.

Luck would have it that the car was still under warenty and the guy I bought it off has covered the cost for a local garage to play about with it for the past 6 weeks.

He had tried Ox sensors etc. and reseting the codes but the light just returned after a couple of days.

Now over a week ago he put a cat cleaner in and reset the light again and low and behold it has not come back on. Is it possible that this could of cured the problem :question

[Proz]

I found the only cure for mine was a new cat ...... but hopefully your emission light wont come back on 

[Entwood]

The only times I've had this fault, and it's been 4 times in 2 years is easily quantifiable .. but remember I'm on LPG

It happens 4-6 days after arriving in France. I clear all codes, and the problem does not re-occur until ....

4-6 days after arriving back in UK .... clear codes  problem stays away.

This makes me think there is some difference in the "quality" (butane/propane mix in my case) between the fuel in France and the fuel in UK ... this change in "quality", causes a change in the exhaust gasses which is picked up by  the system as a fault.

Now this might be right or a coincidence .. no idea .. but the question is .. do those folks who get the warning "chop and change" their fuel stations ?? and do those who don't get it ... use the same one all the time

It's a thought ..... 

[VXL V6]

The only times I've had this fault, and it's been 4 times in 2 years is easily quantifiable .. but remember I'm on LPG

It happens 4-6 days after arriving in France. I clear all codes, and the problem does not re-occur until ....

4-6 days after arriving back in UK .... clear codes  problem stays away.

This makes me think there is some difference in the "quality" (butane/propane mix in my case) between the fuel in France and the fuel in UK ... this change in "quality", causes a change in the exhaust gasses which is picked up by  the system as a fault.

Now this might be right or a coincidence .. no idea .. but the question is .. do those folks who get the warning "chop and change" their fuel stations ?? and do those who don't get it ... use the same one all the time

It's a thought ..... 

My previous 3.2 put the emissions lamp on within a few days of resetting it, I always used Shell Optimax with the vary rare occasion i put BP Ultimate in.

Ultimately while better fuels have better detergents the fault will always be failing pre-cats (Last 3.2 had 79K, this one has 78K now with no P0420/30 codes) and as they do so little anyway it's far better to just move the O2 sensors as per Kevin's advice.

I did try cataclean, it may have helped for a few days but eventually the emissions lamp returned.

I was wondering if it was possible to put 2.5/3.0 cats on (without the precat of the later cars and fit the later O2 sensors and move the original precat ones), guessing the early single cat per side items were less restrictive??

[Big_Roger]

Hi
Is your problem gone away??
In one word, No. I tried Cataclean.

You may get up to 3 weeks with no light, but it will be back.
Did read somewhere that someone in the States was working on a bit of electronic trickery to get round this.

Do we not have any electronic whizz kids on OOF to put their minds to this problem and work out a simple fix??

Roger

[pscocoa]

The only times I've had this fault, and it's been 4 times in 2 years is easily quantifiable .. but remember I'm on LPG

It happens 4-6 days after arriving in France. I clear all codes, and the problem does not re-occur until ....

4-6 days after arriving back in UK .... clear codes  problem stays away.

This makes me think there is some difference in the "quality" (butane/propane mix in my case) between the fuel in France and the fuel in UK ... this change in "quality", causes a change in the exhaust gasses which is picked up by  the system as a fault.

Now this might be right or a coincidence .. no idea .. but the question is .. do those folks who get the warning "chop and change" their fuel stations ?? and do those who don't get it ... use the same one all the time

It's a thought ..... 

Interesting post - I generally always buy Sainsburys fuel but this week filled somewhere else (Total) and light came on today when my wife was driving. Code P0420 has been cleared and cat is working according to VX.

I have not put any top grade stuff for quite a while but will do so now when I can and see how it goes. Cat has done over 90,000 now.

[Kevin Wood]

Mine used to come on after a change of fuel brand - until it came on constantly! I think if the cats are on the edge of working the slightest change of fuel trim will push the monitoring over the edge but they then deteriorate further.

None of this will affect MOT emissions because only the pre-cats are monitored and the main cats will clear up whatever they miss.

If under warrantly I might push for a new pair of cats - you never know, but then if non-genuine ones are fitted you will be worse off.

Relocating the Lambda sensors is one fix. There are ways of fooling the ECU electronically but I have never tried this. Keep meaning to have a go some time.

Kevin