Intermittent fault control system failure

[wjwren]

My 2004 645i has a wobble now and again. Has anyone else experienced this, I dare say it's not just my model of car that has it.

I'm driving along and sometimes the engine cuts out all the controls etc for a split second then comes back on. The car is in limp home mode. I have a flat tyre warning come on and control system failure on the dash. It may occasionally say transmission failure.
Occasionally the sat nav will become fuzzy and unreadable. Again this maybe a separate issue.

Can anyone shed any light please
I did put a code reader and it came up with p0492. I'm unsure if this is related. Any help appreciated as I do love the car.

[anonymous-user]

Battery OK?

[wjwren]

The battery was replaced with a bosch about 2 years ago. Is it true you have to have the battery programmed to the car? I just swapped it out.

[BFleming]

wjwren said:

The battery was replaced with a bosch about 2 years ago. Is it true you have to have the battery programmed to the car? I just swapped it out.

The modern AGM 'start/stop' batteries need to be programmed to the car; the older ones do not.

[wjwren]

is that something i can do at home or would a garage be needed and normal garage or bmw specialist? thank you

[BFleming]

wjwren said:

is that something i can do at home or would a garage be needed and normal garage or bmw specialist? thank you

Apologies; my point was that your car wont have an AGM battery, i.e. no start/stop, so there is no coding required.

[RUSSELLM]

Do you get the impression that the car is losing all electric, momentarily?

[wjwren]

^ yes. I feel like its some type of electrical fault. I thought possibly it might be an alternator issue - i read on another forum about the alternators going and not the correct current going through to the car. I turn the engine off, turn it back on and it goes away.

Edited by wjwren on Sunday 20th October 22:44

[wjwren]

sounds very similar

https://www.bimmerforums.co.uk/threads/urgent-driv...

[RUSSELLM]

If the whole car’s going dead, i’d start at the obvious stuff.

Battery terminals.
Neg lead from battery to body.
Pos lead to mega fuse.

Never had to do it myself, but check the mega fuse for continuity, and give it a little tap, to see if it goes open circuit.