Third limp mode already

[Vintage]

Originally Posted by crystalworks

How old is your battery? Alternator? With any limp mode on a modern BMW... Those are my usual starting points. We just had trans failsafe and codes on the wife's '10 diesel. Nothing since changing the battery a few months ago. Checked battery coding and it was time. First battery got 75000ish miles. We just replaced this one at 155000 miles. So seems they are good for about 75k miles.

BTW, also had a couple of "warning chimes not available" errors that helped point to battery. Yours may not be electrical system problem... But worth checking.

Hi,

My alternator is brand new. Just replaced it last week. Ive checked the battery aswell. And no abnormality there, seems to be in a good condition. Havent replaced it tho. The car is 74k ish miles. I replaced many parts including,

- crank sensor
- cam sensors
- alternator
- waterpump
- all the belts
- all the shock absorbers
- other suspension parts
- brake pad, disk
- tensioner
- coils and spark plugs
- whole valve cover
- all the fluid flushed and replaced
- calibrate the injectors

And i forgot the rest.

Ive checked the voltage on the battery itself, and it was fine. The limp mode is intermittent.

The symptoms before limp mode are, it wont change gear at 3000rpm and keep accelerating then it pops up. With the 4x4 indicator. Dsc communication failure, brake indikator, and i forgot what else. I’ll attach the photo.

Regards,
Adera

[crystalworks]

Always those same codes after clearing? I had different trans codes that popped up, 4e86 I believe being one of them. 4f95 also for clutch monitoring. As well as a couple others in other systems.

No problems since battery change... About 1000 miles ago. BMW modules hate voltage fluctuations... Up or down.

It's just a thought, low trans fluid or bad connections at the mechatronic are also possible as others mentioned.

[josiahg52]

I had some of those odd codes, as well, as my battery slowly died. Since I replaced the battery, I have no DTCs at all.

[Victorious4.8is]

My X5 has its battery replaced the night I purchased it. It was throwing all sorts of warning lights and didn’t even want to change gears. Replaced the battery and all seemed to be well. A few weeks later though the alternator slowly started charging less and less, intermittently dipping under 12v. I’d have to recommend a new battery as a starting point, and, double check the alternator under a full load. Blast everything electrical in the car, bright lights, ac, seat warmers, rear defroster, emergency flashers, etc.... then check your charging voltage to confirm the new alternator is charging as it should. Also, Your battery could have a weak or damaged cell and still test fine. You stated you just replaced the alternator so there is a good possibility that your battery could be damaged or in the early stages of failure as well. A faulty alternator or battery can wreck havoc on any vehicles electrical system and can surely cause a BMW to go bananas! Not sure how old your battery is but if you can’t determine its age it may be time for a new one. That way you can trouble shoot with a known good charging and starting system. Electrical troubleshooting can be time consuming and you don’t want to begin swapping parts. Start with a solid foundation and work from there. Hope some of what I said helps. Good luck!


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