BMW E39 523i - MOT Emmissions Failure - BMW E39 523i - ack1906

I have owned a BMW 523i for about 6 months now. Bought it as a stop gap when I gave back my company car till I could sort out a proper new car. Well, now I have bought myself a 59 plate Merc CLC and was going to put the Beemer through its MOT (which expires this week) and sell it. It failed however on CO2 emmissions upon staart up. Twice. The garage said it need a catalyst. Apparently for this model it is a 2 in - 1 out (pipes???) and available only from BMW at a cost of 800ish. Alternatively I can buy 2 new after-market units and have them welded in place at a cost of 160 for parts plus labour (4 - 5 hours).

I have been told that I may be able to solve the problem by fitting a Lambda Oxygen Sensor and retesting. Have ordered the part and waiting. Assuming this doesn't solve the problem, is there any other way around this? The car is to good to scrap - sweet engine, smooth gearbox and have replaced rear brakes, front tyres and given her an oil and filter service recently.

Ideas?

BMW E39 523i - MOT Emmissions Failure - BMW E39 523i - elekie&a/c doctor

Can you post the mot emission results?Have you had any diagnostic readings taken.I would not rush to replace anything just yet.Btw I think this model could have 4 lambda sensors.hth

BMW E39 523i - MOT Emmissions Failure - BMW E39 523i - ack1906

Can you post the mot emission results?Have you had any diagnostic readings taken.I would not rush to replace anything just yet.Btw I think this model could have 4 lambda sensors.hth

It says "exhaust emissions carbon monoxide content at idle excessive (7.3.D.5)", and then "exhaust emissions carbon monoxide content after 2nd fast idle excessive (7.3.D.4).

On the fast idle test, the CO actual value was 0.555, and on the 2nd fast idle test 0.545. On the natural idle the Co % was 0.542.

Hope this helps?

BMW E39 523i - MOT Emmissions Failure - BMW E39 523i - ack1906

Also forgot to mention it is an auto and has just under 170k on the clock.

BMW E39 523i - MOT Emmissions Failure - BMW E39 523i - unthrottled

HC and lambda value?

BMW E39 523i - MOT Emmissions Failure - BMW E39 523i - ack1906

Fast Idle Test: CO: 0.555, HC: 167, Lambda: 1.020

Second Fast Idle Test: CO: 0.545, HC: 193, Lambda: 1.014

Natural Idle Test: CO: 0.542

Thanks.

BMW E39 523i - MOT Emmissions Failure - BMW E39 523i - elekie&a/c doctor

The lambda and Hc readings are within spec.It is only the Co that is out.This does suggest that cat is in trouble.I would try some petrol magic in the tank and go for a longish hard drive to get the system to max temp.hth

BMW E39 523i - MOT Emmissions Failure - BMW E39 523i - ack1906

Thanks for that. Petrol magic?

BMW E39 523i - MOT Emmissions Failure - BMW E39 523i - unthrottled

yup, The ECU is keeping the mixture in check so no lambda sensor problems or MAF problems.

BMW E39 523i - MOT Emmissions Failure - BMW E39 523i - TeeCee

Thanks for that. Petrol magic?

I think that's code for "a tank of premium quality petrol, chuck in a bottle of redex or similar magic snake oil and take it for an Italian tuneup[1].".

If it does the trick you've saved yourself an expensive cat job. If it doesn't, you've had a bit of fun, you'd probably have bought the fuel anyway and the additive didn't cost much, so you have nothing to lose.

[1] Which is, in turn, code for "drive it around like a stereotypical Italian", although the hyperactive gesticulation and frequent use of the horn is optional.

BMW E39 523i - MOT Emmissions Failure - BMW E39 523i - ack1906

Sounds like a plan. I will thrash her around Norfolk's B-roads before taking her in for her retest then. WIll get some redex too. Many thanks.

BMW E39 523i - MOT Emmissions Failure - BMW E39 523i - elekie&a/c doctor

This is the product I was suggesting

www.ebay.co.uk/itm/PETROL-MAGIC-injector-cleaner-M...4

BMW E39 523i - MOT Emmissions Failure - BMW E39 523i - ack1906

OK, update to this. In addition to the emissions failure problem, it seems ot have developed a further fault. Whereas over the last 6 months, it only did the following twice, it has done it daily now for the last 3 days. When starting from cold, it will give a transmition failure warning and the car will be misfiring. When you switch it off, lock the car (I assume the system resets itself) and start it up again, it is fine. I had driven her yesterday evening for a few miles and she did this again this morning, I took her for a really hard drive for about 10 miles round trip and brought her back. Just don't know whether it is all linked, or whether if i manage to get her through MOT she will develop a further fault, perhaps with the gearbox?

BMW E39 523i - MOT Emmissions Failure - BMW E39 523i - Collos25

An intremitant misfire on a E39 is either one of the coils breaking down or one of the Lamdas past its sell buy date.

 

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