ECU Soft Reset - Battery Died

[Damon]

Hi all

My 2003 3.0 was overwintered and the battery went totally flat - I've got myself new battery and all ok, but there is an EML light on the dash now, which wasn't there before. Is there a way of me resetting the ECU and hoping it will clear? I've got a mobile diagnostic appointment booked already, but hoping to save myself £50 for the privilege as I don't believe there are any issues, other than a bit of memory loss!

Looking to sell the car soon, so this is the worst time to have a light come on!

Any help/ideas appreciated. Pic attached should anyone be interested, but will be posting a for-sale ad in the right thread soon enough...

Cheers, Damon

 

[ph001]

First I would try disconnecting the battery again for 5 mins then reconnecting and going for a drive - the light may go out by itself. Ideally if it's had the same fuel sat in the tank all winter you could siphon that out and put some fresh in, or just fill it up with fresh if it's almost empty anyway.

Failing that a code read is the only way to go I'm afraid. Buy something like C110+ scanner on Amazon with Prime and you will have it tomorrow, then sell it on Ebay for about a tenner less than you paid for it.

Other thing worth checking is that it hasn't gone into transport mode (although this doesn't normally bring the EML light on). Does the air con work, rear heated screen, all fan speeds work as they should?

 

[srhutch]

Also make sure you cycle the ignition at least 5 times (starting the engine) as some of these clear themselves after a number of cyles when the error isn’t found.

 

[Jembo]

I’ve had to totally disconnect the battery as presently being stored in another secure facility with other hibernating cars - right faff transporting on trailers etc...

Dreading if a long term disconnect will cause unwelcome challenges.. though know where to ask

 

[ph001]

Dreading if a long term disconnect will cause unwelcome challenges.. though know where to ask

It shouldn't. The electronics don't really know the difference between 10 minutes and 10 months when the battery is completely disconnected. Problems sometimes arise when the battery is left connected and then slowly drains over time - this is what causes the car to drop into transport mode. Of course, even that is isolated to the cars that did not have their PDI done properly at the dealers from new where transport mode should have been deleted rather than just disabled.

 

[Jembo]

Dreading if a long term disconnect will cause unwelcome challenges.. though know where to ask

It shouldn't. The electronics don't really know the difference between 10 minutes and 10 months when the battery is completely disconnected. Problems sometimes arise when the battery is left connected and then slowly drains over time - this is what causes the car to drop into transport mode. Of course, even that is isolated to the cars that did not have their PDI done properly at the dealers from new where transport mode should have been deleted rather than just disabled.

Thanks Phil, having disconnected when doing GROM/changing bulbs thought would be exactly as you described, just didn’t know 100% for certain.

If it works just fine, next year I’ll
- remove the battery in its entirety
- click the boot lock catch so it doesn’t fully shut
- stick the battery on its ALDI solar charger in the shed to keep it alive & kicking, which did a brilliant job over 4 months before the last move

Cheers & apologies 4 thread hijack