PO140 error with Engine management light

lynxjock · Post by **lynxjock** » Mon Feb 07, 2011 4:12 pm

Hi all, my final niggly point with the old girl, she is an 2004 4.8is and this light keeps coming on, I had it into main dealer who said it was PO140 which was a catalytic converter problem and promptly wanted me to part with alot of money, Had the exhaust checked at a few other garages, emmisions etc and all fine and emmisions spot on, exhaust seems fine too, I had it to a few other diagnostic specialists who could not pin point a fault, lambda sensor, heater element on sensor on sensor all showing okay, I reset it with my peake and within 20 miles or so back on with the light, i'm almost at the stage of just ignoring it but it bugs me, anyone else had this ?

phill · Post by **phill** » Mon Feb 07, 2011 5:31 pm

I had the same on the 4.6 in the end I had both cats replaced. The car passed it's MOT. The reason I changed the cats was that if I decided to sell the car at a later date I would probably have to have them done then and I would have not had the benefit from them, so I saved up and then had them done when I could afford them. It does not seam to effect the running or the performance of the car.

Have you tried hitting the cat with the flat of your hand if it rattles i.e. it sounds as if there are small stones rattling on metal it means that the honeycomb inside the cat has started to break down.

Phill

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lynxjock · Post by **lynxjock** » Mon Feb 07, 2011 8:41 pm

hi phil,

I have had the full exhaust inspected by 3 different garages and all say the exhaust system is fine, they all think the Cat's are okay

phill · Post by **phill** » Mon Feb 07, 2011 9:28 pm

Your symptoms sound very similar to mine in the fact that once the light was reset, if I did short journey's the light would not come on, it was only if I did a longer journey of about 30mins.
The exhaust system looked in good condition and as I said there was no loss in performance, just the light coming on. I cannot remember the P code, but it was something to do with cat bank 1, I will have a look at work tomorrow to see if I wrote it down somewhere.

The only reason for changing the cats was to remove the engine light, it was done in October and since then the light has not come on.

Phill

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lynxjock · Post by **lynxjock** » Tue Feb 08, 2011 10:56 am

hi Phil, should it turn out to be the cats, where did you buy from and what was the cost ?

phill · Post by **phill** » Tue Feb 08, 2011 11:46 am

My cats were Â£670 each plus VAT and they came from BMW as I could not find anybody who do on the shelf after market one's (they do them for the 4.4). Yours are the same as mine I believe.

How many miles has your car done and has it got a full BMW service history. The reason I am asking is BMWUK expect the cats to last for 100,000miles (that is there suggested life time of a cat) if yours has done less you maybe able to contact them for a good will gesture.

I did try FAB direct (BMW scrapyard) for a second hand one, but they were not that much cheaper. There are also companies out there that will make you one.

cats 4 you - gave me a good price but needed the old cat for 2 weeks to replicate - I could not manage without the car for that long.

My car had both cats changed, I have not got the P code but the codes were cat bank 1 and cat bank 2, so both cats were faulty.

Hope the above info is of some use.

Phill

Sundayjumper · Post by **Sundayjumper** » Wed Feb 09, 2011 11:21 am

[quote=""phill""]I did try FAB direct (BMW scrapyard) for a second hand one, but they were not that much cheaper.[/quote]
FAB ? Expensive ? Well I never !

I do wonder how they've stayed in business for so long with the prices they ask for. Way over the top IMO.

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