Ford Focus 1.5 TDCI possible battery issue

Have you tried clearing the errors

12.6v right after driving is residual charge from the alternator, ideally a battery should be tested for voltage after it's been sitting for a few hours, or even overnight and check the volts first thing in the morning, that would be the "true" reading, providing there's no parasitic draw.

My battery sits around 12.2v when tested with the above method, although it's about 6 years old so doing well, 10 years old I'd definitely replace it if you think there's an issue with it.

As above,clear codes and see what comes back to see what DTC is genuine and what was just because battery voltage dipped too low.

Don't put a regular battery in a car that requires a stop/start. Technically it will work. But might not last anywhere near as long. Those stop start batteries are heavy duty and expensive for a reason, and usually have to send a lot more power to the starter motor which is a hefty, tandem solenoid starter motor for stop/start equipped cars. so a regular battery may lead to longer crank times.

11.8v battery is dead as a doornail, it's able to take a charge from the alternator while driving, but not hold a charge when engine is off, i.e needs replacing.

quick and approximate way to think of it is a 12.6v battery loses 10% state of charge (SoC) for every 0.1v less that it measures

So,

12.5v is 90%

12.4v is 80%

12.3v is 70%

And so on..

Obviously colder ambient temperatures can affect the readings, so it's to be taken with a pinch of salt.

Yours in the photo is a stop start battery.

See where it says Enhanced flooded? That's known as EFB and that's what you'll see on listing's. EFB batteries are used for stop start, other types are AGM and are also used as stop start batteries. So that's how you'll know it's suitable for stop/start.

Just buy another battery with the part number on that one or you can use the information on the green strip. The 75Ah and 700A should be the same at least, you can get higher numbers of those for an upgraded battery, at an increased cost. And just make sure the terminals are in the correct orientation, I know on that car the closest terminal to you is the positive.

On that, it's a pain in the hole of a battery to change, airbox needs to come off, fair bit of unclipping, and even then it's well recessed and it's not light so mind your back pulling it out if you're doing so yourself.

Upside though, you do not need to code the stop/start battery on modern fords when replacing, they have a passive re-learning system in place that will do it for you over a day or so after install, I've had this confirmed by my local Ford main dealer.

You can still go into settings with a scan tool and relearn it the usual way, for peace of mind.

Once it starts it'll be charged to above 14v by the alternator so I'd say you'll be grand. Bad batteries can cause a lot of codes to pop up on modern cars because so many systems require a healthy battery voltage to operate the system sh1ts itself when it thinks it doesn't have the required volts. I'd imagine the vast majority will clear with a new battery installed except for the right rear ABS sensor and steering angle sensor are related to each other, and the bulb.

Plenty info on YT. Look up 1.5 and 1.6 diesel battery replacement for focus,kuga,mondeo, they're all the same.

I did the job on a Kuga, much less space as the engine bay is "shorter" , you'll have more space in the focus, have a good trim removal tool there's 3 or 4 plastic push pins that hold wiring to the front plate that covers over the battery, they are very tight to come out,I ended up just cutting the cable ties around the battery but it was the height of winter more of an emergency repair and I had limited tools with me.

I'd remove the ground stud to the right first thing, most just remove the positive because it's closer but you risk shorting out the system with the negative still connected, it's located here, there will be sparks,don't worry about it,think it's a 12 or 13mm wrench or long hex socket needed

This is a decent video on it. Best of luck

Would the new battrey have to be coded to the car ? Mk5 mondeo and im sure i coded it 2.0 tdci

I'm getting similar issues on my BMW 3 series.

The ABS sensor is gone. Caused by warping/expanding of the Reluctor ring / ABS ring. I know this because when I removed the sensor on the wheel side I could see scraping marks. My ABS ring has ribs on it which cause the chafing when it expands over time.

Your vehicle seems to have a magnetic Reluctor ring, so shouldn't cause that chafing. However, the ring itself could have cracked and is not working as expected.

I would suggest replacing the ABS Sensor first. It shouldn't be a be a problem to do so, as explained above. It should be a DIY job. YouTube it for your vehicle.

Check Autodoc or similar sites for pricing for the sensor. It's a very simple sensor so doesn't need to be bought from Ford.

As a side note, I noticed on that video if you did want to or need to replace the wheel bearing assembly it's just 4 simple bolts, only Ford decided to use "E-torx plus" bolts for them, which means basically every single person who tries to do this repair DIY will have to go off and buy another set of sockets.

Just an example of manufacturers trying to discourage people from doing their own repairs.

Had this issue in the wife's Focus. Replaced the battery with a new one as it was the original battery in it still and could do with replacing at 8+ years old I thought. Issue still persisted.

Then replaced both ABS sensors in the rear, which were handy enough to do. A quick drive and faults all cleared and haven't come back since.

Trickiest part was having to use my phones selfie cam as a mirror to see what I was doing tbh

but never tried changing break discs or pads yet,

This is not me being a grammar nazi, but just an observation on something that happened recently while doing a Google search for car breakers. Pretty much every result was about car brakes. I don't know if this is caused by predictive text or people just misspelling 'brakes', but it got me thinking about how AI and search engines could fall foul of text speak and other shortcut spellings or misspellings.

Sorry for going OT.

Ah yeah, as I said, not having a go. Just interesting to see how Google can be fooled. Garbage in garbage out as we used to say. AI is not going to take over the world. 🤣