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Steve
Steve, BMW Expert
Category: BMW
Satisfied Customers: 24425
Experience:  BMW Expert
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I have a 120d 1 series. It's 55 plate There is an

Customer Question

Hi
I have a 120d 1 series.
It's 55 plate
There is an acceleration problem. The A traction flashes and it jolts (like an old spark plug issue)
Then all of a sudden it dings. The a traction comes on as well as the ABS and they stay lit however the car then drives normally.
Can you help please
Submitted: 1 month ago.
Category: BMW
Expert:  Steve replied 1 month ago.
the lights ultimately stay on indefinitely?
Customer: replied 1 month ago.
No. When I turn it off they go out and the process starts again. Because I don't like the jerking I've noticed that it I really put my foot down. This forces then on quicker so I can drive normally.
Customer: replied 1 month ago.
I want to just sell it but the buyer is either going to have he fault lights or the jerking.
Expert:  Steve replied 1 month ago.

Please do not forget to click a positive rating as this is the only way I receive credit for my answer, thank you

the problem is that the abs/traction control system is cutting in when it should not be

for some reason, the system either thinks the car is slipping, or there is some other issue with the abs/traction components causing the system to cut in when it should not

if the lights stay on, this means that faults should be set in the abs/traction control module which can be read out with a scan tool.

alternatively, a bmw scan tool can also be used to monitor the live data from the system and identify what is cutting in.

Please let me know if you have further questions. Please do not forget to click a positive rating as this is the only way I receive credit for my answer, thank you. Best wishes with your vehicle.

Customer: replied 1 month ago.
Are you saying that it is normal for the and trac system to cut in when there is a problem. Ie. It is designed to kick in to temp deal with the fault. This would make sense.
So I need to get it investigated as to why it's jerking in the first place and this will be the solution to the problem is this correct? Or is it correct that when it kicks in tbis operating normally?
Expert:  Steve replied 1 month ago.

Please do not forget to click a positive rating

no, it is not normal. what you are experiencing is not normal operation

it is designed to kick in when the car is slipping only, not when there is a fault. if it is cutting in when the car is not slipping, it is the fault causing this, not some kind of back up that makes it kick in just because there is a fault detected.
there is a malfunction that is making it think the car is slipping, or making it cut in for unrelated reasons
you need to have the diagnostics I described carried out to verify what is either making it think its slipping, or what is making it cut in randomly. Please do not forget to click a positive rating

Customer: replied 1 month ago.
what about the fault with the car jerking and the A light flashing on and off as the acceleration is compromised? Would I assume that this is a different problem? Ie the cause of the problem? I find it strange that the abs/trac coming on actually fixes the issue.
Last question donyou think it would be expensive to fix?
Also I forgot to mention I have an oil leak and the garage said that it would be expensive to even identify the origin of the leak. Looks like my only options are to spend lots or scrap it?
Expert:  Steve replied 1 month ago.

Please do not forget to click a positive rating

when the traction light is flashing, this is the traction cutting in because it thinks the car is slipping

when the lights come on permanent, this means the system is fully disabled, that's why the issue goes away

it is all one issue related to the abs/traction fault

cost completely depends on the component at fault, if a simple sensor it will be very cheap. if the control module or pump, expensive.

The oil leak is technically a different question per site policy and should be posted as its own question. I would be happy to answer your question about the oil leak free of charge, but cannot do so until I receive proper credit for my complete answer to the original question, via positive rating.. Please do not forget to click a positive rating

Steve and other BMW Specialists are ready to help you
Expert:  Steve replied 1 month ago.
I would not expect an oil leak to be expensive to trace, perhaps a few hours labor at most.
even if the oil leak is a relatively expensive one, there are only a few leaks that could justify scrapping the vehicle.
Customer: replied 1 month ago.
Ok. Thanks for your advice.
The details on the abs kicking in totally make sense. It used to slightly come in when going fast. It sounds like hopefully a sensor issue.
Would you recommend taking it to any garage or a BMW garage. I have limited funds and as it's old I don't want to spend a lot.
Expert:  Steve replied 1 month ago.
bmw specialist only for this. without question.
Customer: replied 1 month ago.
Thanks for all your advice. I'll update you with the outcome
Expert:  Steve replied 1 month ago.
you are welcome