Focus ST

[theshrew]

Had my car go into limp home mode a couple of times lately then it clears itself. Normally when it's colder weather.

I've had a feeling the battery was on its last legs for a while to. This morning I came to the car and it was flat. Managed to bump start it but it went into limp home mode again.

Could low battery voltage cause this ? Or is it just randomly happend at the same time ?

I wouldn't imagine low v to cause this but it just seems strange that the bat was on its last legs and it only happens when it cold. It's happend twice when I've just nipped to the shop at night so the bat won't of had chance to charge again by the time I get to the shop.

When it's not in limp home mode the car runs fine no misfire or anything like that.

[Magic919]

Yes. No.

[Justin S]

Just change the battery if you think its not in the best health.

[theshrew]

Justin S said:

Just change the battery if you think its not in the best health.

I changed the battery this morning.

I was more interested if the low voltage could put it in limp home or if I had another issue.

[Justin S]

Low battery causes all sorts of issues, as the alternator is fighting to keep the car alive and with a dead battery, it can create issues of under voltage, which causes electrical issues, hence why get a new battery first. Is it any better now?

[theshrew]

Yeah its all sorted now. Must of just happend when the battery had low voltage not had it come on since i fitted the new battery.

[neiljohnson]

Be worth having a diagnostic scan & any codes cleared down as low voltage tends to trigger lots of codes which will just sit there until it's next scanned
If you later have an issue it can be very difficult for the problem to be found if the ecu is crammed full of "historic" codes caused by the faulty battery