As per title I had to change my battery today on my Mk3 Focus Estate, 1.6 petrol.

Swap went without a hitch, but when trying to start the car got a dashboard full of warnings, from handbrake fail to engine malfuncion. Searching revealed the need to reset BMS, but so far tried these methods have not worked:

Method 1:

• Ignition on
• Flash high beams five times
• Press brake three times

Method 2:

• Ignition on
• Position lights on
• Flash high beams five times
• Press brake three times

Method 3:

• Ignition on
• Position lights on
• Press rear fog light five times
• Press hazard light three times

No luck so far. Battery should be correct as ordered via number plate at Halfords and all other electricals work fine, but dare not turn on the engine in case the issue is more than just a reset.

Am I doing something wrong, or missing the timing between the actions?

22 minutes ago, ProtoNuco said:

As per title I had to change my battery today on my Mk3 Focus Estate, 1.6 petrol.

Swap went without a hitch, but when trying to start the car got a dashboard full of warnings, from handbrake fail to engine malfuncion. Searching revealed the need to reset BMS, but so far tried these methods have not worked:

Method 1:

• Ignition on
• Flash high beams five times
• Press brake three times

Method 2:

• Ignition on
• Position lights on
• Flash high beams five times
• Press brake three times

Method 3:

• Ignition on
• Position lights on
• Press rear fog light five times
• Press hazard light three times

No luck so far. Battery should be correct as ordered via number plate at Halfords and all other electricals work fine, but dare not turn on the engine in case the issue is more than just a reset.

Am I doing something wrong, or missing the timing between the actions?

Now if you take away the fact it's a ford and that you have replaced the battery n answer it like a general question. That describes what happens when a battery is running out. Obviously yours shouldn't be if its new everything should be working fine. To me l would say that you have been either sold a dud or it's the incorrect type personally l wouldn't trust halfords to unblock a sink given they couldn't even tigjten a bicycle together properly ( wheels / handle bars n pedals ) and there meant to be professionals. I was taught as a kid how to do every bit. I would get the battery tested at a local parts shop or if you have a multi meter see what it's reading and go from there.

Battery Details?

Start/Stop?

Voltage of the new battery? Taken at the battery terminals with a multimeter.

9 hours ago, YOG said:

Battery Details?

Start/Stop?

Yuasa HSB075 Silver 12V 60Ah

Not stop start.

Don't have a multimeter but looks like I may need to invest in one...

So we're saying likely battery fault rather than car reset issue?

1 hour ago, ProtoNuco said:

So we're saying likely battery fault rather than car reset issue?

It looks like a battery fault. It certainly isn't going to be fixed by a BMS reset.

The other thing to try would be to disconnect the battery negative lead for 30 minutes. Then reconnect it but wait 5 minutes before opening any car door. That might allow some modules to reset.

1 hour ago, ProtoNuco said:

Yuasa HSB075 Silver 12V 60Ah

Not stop start.

Don't have a multimeter but looks like I may need to invest in one...

So we're saying likely battery fault rather than car reset issue?

The only ther thing l could say that would cause it to do that is if 1 of the black earth wires isn't connected properly or it has corrosion on and it's not allowing the electricity to pass through properly ( changing the battery could have knocked 1 of the wires at a position of just out of view ) it's worth looking as it might save you the time and money trying a lot of other things.

Did you fully charge the new battery before installing? They are not supplied fully charged and the SOC may be low.

Your 2012 Focus doesn't have a Battery Monitor System (BMS) fitted.

The car just uses the old standard 'not so smart' charging system, which is actually a lot better than the newer Smart charge.

2012 diesel Focus does have a BMS and stop start.  I can't speak for the 1.6 petrol though. 🤔

4 hours ago, TomsFocus said:

2012 diesel Focus does have a BMS and stop start.  I can't speak for the 1.6 petrol though. 🤔

According to the early Mk 3 brochure I have, start/stop was only available on 1.6 Ecoboost and 1.6 TDCi engines with manual gearbox. 

Happy to report the issue is resolved!

After re-doing the whole change again just to test if it was the battery, I found the culprit: a loose and/or slightly dirty cable that leads to the fuse box.

I had actually tried reconnecting it a few times during this ordeal, to no effect. What finally solved it was spraying it with some electric contacts cleaner, waiting for it to dissipate, and carefully reconnecting it.

That's it, car starts & runs fine, not a warnig light in sight!

48 minutes ago, ProtoNuco said:

Happy to report the issue is resolved!

After re-doing the whole change again just to test if it was the battery, I found the culprit: a loose and/or slightly dirty cable that leads to the fuse box.

I had actually tried reconnecting it a few times during this ordeal, to no effect. What finally solved it was spraying it with some electric contacts cleaner, waiting for it to dissipate, and carefully reconnecting it.

That's it, car starts & runs fine, not a warnig light in sight!

Happy days 😎👍 if it's 1 that corrodes so easily over 10 yrs I'd be putting some protective stuff on it to reduce the chances of it happening again, when mine went it was only 1 hr after I'd last used it. Prevention is better than the headache later 😂

6 hours ago, TomsFocus said:

2012 diesel Focus does have a BMS and stop start. 

All I can say in that case some do and some don't !! 🤔

Perhaps introduced part way through 2012 ?

 

12 hours ago, unofix said:

All I can say in that case some do and some don't !! 🤔

Perhaps introduced part way through 2012?

Perhaps.  Mine was built in June 2012.

Though I would expect all of the manual 1.6 TDCI to have SS, as they were all £20 tax band as far as I know.

We did also find that the Mk2 Econetic trim had SS in 2010 (1.6 TDCI with £0 tax), so Ford did have the tech available at Mk3 release.

13 hours ago, unofix said:

Perhaps introduced part way through 2012 ?

Just checked my old brochure and it's dated December 2010, so looks like S/S from launch on the 1.6 Ecoboost and 1.6 TDCi (manual).

22 hours ago, unofix said:

A 2012 Focus doesn't have a Battery Monitor System (BMS) fitted

I beg to differ. Our old Mk3 1.0L Ecoboom Titanium Estate VIN WF0LXXGCBLCE84823 first registered 11/09/2012 definitely did.

 

4 hours ago, mjt said:

Our old Mk3 1.0L Ecoboom Titanium Estate VIN WF0LXXGCBLCE84823 first registered 11/09/2012 definitely did.

I think the 1.0 ecoboost got S/S (and presumably also BMS) from its introduction.

The OP was talking about the non-turbo 1.6Ti-VCT though, which still didn't have it in the 2014 MY brochure.

It did also have stop-start. I tried to add that to my post above but got hit with the Cloudflare outage.

Thanks for the clarification Roger.

So back to the OP's problem of not being able to reset the BMS on his car.

I still maintain that his 2012 Focus doesn't have BMS hence the reason he can't reset it.

16 minutes ago, unofix said:

I still maintain that his 2012 Focus doesn't have BMS hence the reason he can't reset it.

Assuming it is a 1.6 Ti- VCT, everything I've seen and mentioned here suggests that you're correct.

Perhaps the OP (ProtoNuco) could confirm whether his car has BMS or not, because all he's confirmed is it now 'starts & runs fine' after fixing 'a loose and/or slightly dirty cable that leads to the fuse box.', but not if he reset a BMS!

On 11/18/2025 at 11:26 PM, YOG said:

Perhaps the OP (ProtoNuco) could confirm whether his car has BMS or not, because all he's confirmed is it now 'starts & runs fine' after fixing 'a loose and/or slightly dirty cable that leads to the fuse box.', but not if he reset a BMS!

I did not reset it, so guessing I might not have it.

Easy enough to check. If there isn't a BMS sensor attached to the battery negative terminal as shown in my earlier post it doesn't have it.