Hi,
I replaced the battery in my 2006 Forester today and now it won't tick over, it was perfect before. Could this be that the ECU has to relearn things before it will tick over?

Aedan

 

Sounds more like the ECU has 'learned' to live with a degrading sensor. Since you changed the battery, the ECU may of reset and 'forgotten' the fault.

A quick diagnostic check should pin point the problem, CTS, IACV,TPS ect.

 

Dud battery? I bought a new battery from Halfords a couple of years ago and put it in the car and it wouldn't turn over - took me ages to figure out that it was actually the battery (as I naturally assumed with it being new it would be perfect). Turned out there was no current coming from it and it was a "dud". Swapped it with another new battery and worked first time.

 

 

A quick update on this...

I took the car to my garage yesterday and they could not find anything wrong. The general opinion was to try driving it for a while and see if it learns how to tick over in time. I did a couple of long trips today but no change so far.

Aedan

 

If this was a MY99 i would be looking at the MAF sensor, by removing the battery will have reset the ECU, unstable idle normally indicates a faulty MAF after a reset, it does not allways show up on select monitor, however you can measure the voltage output to test, don't drive it hard untill you sort it out, because if it turns out to be the MAF it will run lean on boost

 

I assume the garage checked the new battery was ok and not the cause of all this (strange that it all happened since fitting the new battery)? As a process of elimination did they swap for another battery? It could still be this if the new battery isn't supplying enough charge but enough to get it running.