Fault codes serious or not?

[PliSsK]

Had the yellow engine warning light come on recently on the dash a couple of times on my 2001 E39 Alpina B10 V8 (540i equivalent). Manual defines this warning light as 'deterioration of exhaust emission control values'.

I had had the following fault codes, mainly OF 1A, which I have had occasionally over the last 6 months, but in the last week, frequently.

- OF 1A - Mixture Control Off Idle Cyl 1-4
- OF 72 - Camshaft position sensor Cyl#5-8
- OF 66 - MFL Interface

Going to get the car serviced in 3 months. Question is, are the above indicative of anything serious? Does it need urgent attention? The engine seems to be running fine. Not noticed any problems with it at all.

Thanks in advance.

Edit: UPDATE: It was the MAF sensor. Replaced it and no more fault codes. See my last post for details.

[328 Power 04]

Yes, you need to service it now. Mixture codes and camshaft position sensors are not something you wait on, if you like your car.

[bmwdirtracer]

+1.

You have a very special car, congratulations. But never mind what the manual says: you have codes which indicate a need for immediate attention. You must not let your engine operate in this condition for months. In example, if your fuel/air mixtures are incorrect, you can burn holes in the pistons, and ruin the very expensive engine.

[PliSsK]

Thanks very much for the input and kind words! Will get it booked in asap. BTW, apart from unnecessary mileage, would you advise any other precautions, such as avoiding high revs? Cheers.

[bmwdirtracer]

Oh, hell no. Drive it hard. BMWs need to run, and Alpinas are exquisitely refined BMWs. It'll be happy to be used, don't be shy......but, of course, wait until the fuel/air mixtures are correct, and the computer knows the camshaft position.

[jharbert530]

Just reviewing forums falling in love with the BMW more an more , what's this alpina B10 (you called it the 540i equivalent) so I'm assuming its a European or German model, educate me please !

[bmwdirtracer]

http://www.alpina-automobiles.com/en/

https://en.wikipedia.org/wiki/Alpina

[TonyAngel]

If you don't drive it like it was meant to be driven, it will get bored and leave you for another. Don't let that happen.

[PliSsK]

lol

The engine cut out occasionally since I first got the car in 2013, in lower gears, with the spare key, but not with the main key. Occasionally had problems starting the car (click no crank no start) intermittently over the last 4 years as well as battery charge issues (even with brand new battery). During the end of 2016, it started doing it again with the main key, sometimes in 3rd gear, up to around 40mph. When I tried to restart the car, it would usually do the click no start routine for a couple of attempts and then start up cleanly. The engine cutting out started happening again in 2017, but on a frequent basis. Since I recharged both key batteries a couple of times, it did it only once in Jan and once in Feb (with the same click no crank issue immediately afterwards), I got the fault codes '0F 1A - Mixture Control Off Idle Cyl 1-4' each time. The cutting out issue has not happened since and neither did I get the OF 1A either. The click no crank issue got a lot worse in April and I have since replaced the ignition antenna ring (made no difference) and sanded down the battery connectors the latter seems to have fixed the problem. I started getting the OF 1A fault codes on a regular basis in the last 10 days, along with the yellow engine light coming on more frequently. I don't know whether the engine cutting out was down to mixture control or whether it was key related. Logic would dictate that the key battery is not involved with the immobiliser, so none of this really makes complete sense to me. Anyway, a little extra information, but it seems the OF 1A problem was intermittent but has been getting worse. I think I did around 100-150 miles in the last 10 days when I have been getting the OF 1A regularly. I hope to only do around another 10-20 miles before the car goes into the garage.

Re the model, the Alpina factory bought 540is in an official capacity straight from the BMW production line and with approval from BMW did various updates to them. Here is a review of the car with technical specs etc.

http://www.evo.co.uk/bmw/alpina/14025/bmw-alpina-b10

[328 Power 04]

The mixture control is unrelated to the key and immobilizer. It's a problem under the bonnet.

[bmwdirtracer]

If the EWS (Immobilizer) were involved in the engine cut off, there would be codes for that. However, the EWS system only operated when the car is STARTING, not when the car is running, so that's not the issue.

It's also unlikely that the battery cables are the cause of the engine shut-off, because the engine runs off the alternator, once the car is started. (There's a lot of "yeah, but" to that statement, but I'll leave it, for now.) If the fuse box, or the engine computer, or even the engine main ground wire looses its connection, these places could easily cause your engine cut-off. The engine ground is between the engine mount and the "frame". On a left hand drive, it's on the right engine mount.....I'm not sure, on a RHD. Unbolt it and clean it, and rebolt it, both ends. Then, I'd also recommend opening up the engine computer box, underneath the cabin filters (don't know which side on a RHD), and looking for water ingress to the box. While you're there, unplug all 5 engine computer plugs and spray both sides of each connection with electrical contact cleaner. If you can find it, "Wurth Electrical Contact Cleaner Oil" is the best. Blow the plugs dry with air, and reconnect them. (The engine computer has black plugs, the transmission computer uses blue ones)

Your car IS an E39 5 series car, even though it's an Alpina....and the E39 and E38 both share a failure-prone ignition switch. While I have not ever known this switch to cause engine shut off, I have known it to cause almost every other electrical anomaly. The switch is inexpensive, and easy to change, so you might want to consider that.

You'll note that I haven't mentioned the Mixture code. This is almost certainly not related to your engine shut-down, but you do need to attend to it. I'd start with a smoke test of the intake system, done with a professional smoke machine at a good BMW specialist shop. Such a shop will also know that the back cover plate of the intake manifold (also known as the pressure control valve) is known to fail, and they might want to do a crankcase vacuum test, with a slack tube manometer.

There's a really helpful website for the M62 engined cars, in the UK....but dammit, I just can't remember the name of it this second, sorry. It'll come to me.....or, you can check in over at our 7-series E38 forum, here. It's one of the most knowledgeable groups here, and they know your engine (without the Alpina mods anyway) very well.

[PliSsK]

Thanks very much for the input Chris.

I mentioned all of the above as there seemed to be some sort of loose relationship unless it was coincidence. The click no start issue always seemed to immediately accompany the engine cutting out in 2nd or 3rd gear, and the fault code for the mixture control always seemed to occur at the same time, although it is possible that it occurred at some point prior, after I had last cleared the fault codes down, on each occasion. Interestingly, every time the engine cut out, the road conditions were dry, although that isn't to say moisture wasn't a problem or somehow involved under the bonnet in the electrics. Also when the engine cut out each time, I would always have power to the ignition - the dashboard lights would light up like a Christmas tree when the engine died and stay on until I tried to restart the car again. The car not having the cutting out problem in 2nd/3rd gears after changing keys was strange, and one would assume this was just coincidence, as the key battery has nothing to do with this. I have since swapped between key 1 and 2 for different journeys and not had the cutting out happen at all. I agree about the battery terminal connectors not likely to be involved in the cutting out issue as it would presumably only be a starting issue, unless it was the battery negative terminal ground (?), but I have just recently sanded these connectors down to hopefully prevent any future recurrences of the click/nostart/nocrank issue.

You made some great suggestions and I will certainly be having a look at all of the above to assess if there might be an issue with the ECU box. The rubber trim that guides the water from the windscreen is a little loose on both sides, which might have potentially caused a problem, but it all looked pretty dry there last time I looked. Replacing the ignition switch I presume you mean a BMW sourced one rather than an OE one which might not be as good quality. The ignition switch for this car from factory was the 61326901962, which is still in production now. The ignition switch on the pre-facelift model (1996-2000) was the 61328373061 and it was superceded by the newer switch even on pre-facelift cars. I don't know whether the former resulted in more ignition problems but a new part suggests the newer one might have been a better design. They aren't that costly to replace, you are right, although prices have gone up somewhat with the current bad exchange rate we are having with GBP vs EUR. I haven't had any 'typical' symptoms of ignition switch failure but it could be that the cutting out was ignition related. If it ever happens again, if I haven't replaced it by this time, I will perform the 'visor' test to see if it is actually implicated.

I've booked the car in to get it looked at at a trusted BMW specialist, but will try to look at the fault codes on BMW 1.4.0 when I get it working again on my laptop for my own interest. Thanks for the advice there. I will discuss their plan with them once they have done their own diagnostics on the car. I did read that carbon on the throttle body might cause the problem but I read that there are many possible causes that will require a little poking around. I'll have a wander over to the E38 forum as I realise many of the E38 owners wander over to the E39 forum too as the cars share many parts in common. Cheers!

[thejlevie]

A click but no rotation of the engine could be a problem with primary power to the starter, a high resistance in the starter solenoid lead, bad engine ground, or a bad starter.

[PliSsK]

Update: Got the indie garage to have a look. Apparently idle mixture adaptation was fine at 3ms, but part load multiplicative values were +11% on bank 1 and +8.75% on bank 2, and anything over 10% triggers the OF mixture control off idle fault code. Possible reasons for banks 1 and 2 fuel mixture differing might have been ageing of the lambda sensor bank 1 with respect to 2, a small air leak to bank 1 , a slight engine mechanical fault or an hot film air mass (MAF) sensor that had corroded (reading overly lean, resulting in the engine richening the fuel mixture to compensate). However, given that the engine was otherwise running smoothly, he thought it most likely that it was the MAF sensor playing up. He fitted a new one, which I didn't realise was so easy to do until after I'd asked him to do it, or I would have done it myself and saved a significant chunk of money. However he did do some diagnostics on the fuel mix afterwards and the levels normalised apparently. So it seems that the problem is now solved. I don't know whether he was using DIS to look at these values (I haven't managed to get it working yet on my old lap top), but at least I know for next time what a likely cause might be and how to fix it. Thanks for the input.

[328 Power 04]

A MAF will not fix a camshaft position sensor. Keep in mind.

[PliSsK]

A MAF will not fix a camshaft position sensor. Keep in mind.

This is true. I only had the cam pos sensor fault code come up once, whereas the mix control off idle was coming up regularly. The owner of the garage said he wasn't too concerned about the former. I don't know whether it is true that one fault code can trigger another as is sometimes claimed, as it presumably depends on the specifics of the problem and what the downstream effects of it are. I will keep an eye on it and check regularly for fault codes.

[PliSsK]

Incidentally, when the car was in the garage, the first thing they spotted was a rodent nest under the engine cover and the part of the wire harness that goes between both banks of cylinders was chewed through revealing the wire, which wires of which turned out to be slightly damaged, but luckily we managed to repair them from an existing E39 540i wiring harness he had as a spare. Whilst a separate problem from the fault codes the engine was producing, it might have explained the intermittent engine cutting out issue.

[bmwdirtracer]

I see rodent nests underhood at least once a week. Hell, a few weeks ago, I bought a big bag of sunflower seed for the wild birds, and left it in my own car's trunk, overnight.....only to find a rodent had opened it, by morning. Damn, I hate when rodents get in a car! (And, by the way, I have 4 cats, and 5 snakes....what's up wit dat?)

I guess Alpina set their DMEs up with different parameters for mixture control codes. Most BMWs won't set long-term fuel trim (multiplicative) codes until ~25%. The primary (pre-cat) oxygen sensors should be considered maintenance replacement items.

[PliSsK]

I see rodent nests underhood at least once a week. Hell, a few weeks ago, I bought a big bag of sunflower seed for the wild birds, and left it in my own car's trunk, overnight.....only to find a rodent had opened it, by morning. Damn, I hate when rodents get in a car! (And, by the way, I have 4 cats, and 5 snakes....what's up wit dat?)

I guess Alpina set their DMEs up with different parameters for mixture control codes. Most BMWs won't set long-term fuel trim (multiplicative) codes until ~25%. The primary (pre-cat) oxygen sensors should be considered maintenance replacement items.

What, under the same car, or in the many cars you look at? lol that sunflower seed story is pretty funny. It's a shame your 4 cats can't clean the place up! Yeah, I don't know how long the lambda sensors will hold up, not much longer probably, but is something I think I could replace myself if I can jack the car up. Cheers.

[thejlevie]

I opened the hood of my E30 one cold morning to find a possum curled up on the intake manifold. I guess he/she was looking for a warm spot to spend the night, and found one...

[PliSsK]

lol, I had the back seats tops out of the car for the first time and lo and behold under the covers for the fuel lines were the signs of a rodent bringing in some nest material etc. Not sure if anyone is interested, but to provide an update on the original issue with the car, after replacing the MAF sensor in May, I've done 3 months of motoring without a single fault code, up until today when I had the 0F72 back again, camshaft pos sensor cyl 5-8. My guess is that it was borderline before, hence the fault code concurrently with the MAF related fuel mix fault code. So I will prolly replace both cam sensors myself as it looks pretty simple to do. The car is 60k miles and from 2001 so I think that is round about the expected life of these sensors? Update: replaced the CPS sensors, no fault codes as yet. I suspect the old CPS sensors may have been responsible for the stalling in lower gears I had been getting up until Jan this year.