Issue:

Errors on dashboard of my 2019 Ford Focus MHEV St line car while driving and the brakes become very stiff, making it very hard to brake and unsafe to drive.

 

I have noticed this problem seems to be worse if the engine is allowed to idle while parked for a period, then starting to drive.

 

The problem sometimes goes away briefly when the engine is off and started again, and if car is locked for 10+ mins.

 

Then the dashboard errors randomly return when driving again, causing the brakes to not function properly.

 

 

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Notes:

First garage I took it to says it's a communication error from the ESC system and it likely needs reset.

 

 

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Errors on dashboard:

ESC service required

Hill start assist fault

Collision sensor fault

Check brake system

 

 

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Errors found on OBD Scanner:

P0CA2 - DC/DC Converter step down Voltage Performance - internal electronic failure

 

P1A13 - Hybrid Powertrain Control Module

 

C0049-01 - Brake fluid level - (General electrical failure)

 

U3001 - Control Module Improper Shutdown Performance

 

U3000 - Control Module - (Internal electronic failure)

 

U0415 Invalid data received from anti lock braking system ABS Control Module

 

U0418 - Signal invalid - Invalid data received from brake system control module "A"

 

Lost communication with:

U0131 - Power Steering Control Module "A"

U0100 - ECM/PCM "A"

U0151 - Restraints Control Module

 

 

 

I have it booked in with a local Ford garage for a diagnostic on Thursday but after speaking with Arnold Clark to see if they will cover it through my Autocare warranty, they said they do not have a Arnold clark Ford garage in Scotland, but the megastore might be able to fix it, and it might be covered by the warranty. 

 

I need a working car for work ASAP, preferably by Friday and was just looking for advice on whether I'm wasting my time going down the warranty route? 

 

I only bought this car 9 months ago and this has been a headache over the last week, so any advice would be greatly appreciated! 

 

TIA! 

First: Get a new, main, 12V battery, fully charge it and fit it

Second: Get yourself set up on FORScan and reset BMS then perform a reset on the modules that have the communications issues

Third: Check how many modules require software updates and get them updated (into Ford for that, don't risk doing it yourself👍)

The vehicle 12V battery State Of Charge (SOC) is below the critical minimum level.

Replace the battery with a brand new Yuasa 12V battery. Make sure you charge it for 12 hours before you fit it. Then reset the BMS (no tools required).

 

8 hours ago, DaveT70 said:

First: Get a new, main, 12V battery, fully charge it and fit it

Second: Get yourself set up on FORScan and reset BMS then perform a reset on the modules that have the communications issues

Third: Check how many modules require software updates and get them updated (into Ford for that, don't risk doing it yourself👍)

 

7 hours ago, unofix said:

The vehicle 12V battery State Of Charge (SOC) is below the critical minimum level.

Replace the battery with a brand new Yuasa 12V battery. Make sure you charge it for 12 hours before you fit it. Then reset the BMS (no tools required).

Thank for the information, I did think it seemed battery related, seen as the problem seemed to dissappear briefly after driving and got worse when idle. 

I'll get a new battery fitted and do as yous have said, hopefully this will fix the problems! 

I actually got a Forscan reader yesterday, to check for these faults as my old OBD reader picked up nothing, so I'm halfway there, I will buy a battery now.

Thank you! 

8 hours ago, DaveT70 said:

First: Get a new, main, 12V battery, fully charge it and fit it

Second: Get yourself set up on FORScan and reset BMS then perform a reset on the modules that have the communications issues

Third: Check how many modules require software updates and get them updated (into Ford for that, don't risk doing it yourself👍)

 

7 hours ago, unofix said:

The vehicle 12V battery State Of Charge (SOC) is below the critical minimum level.

Replace the battery with a brand new Yuasa 12V battery. Make sure you charge it for 12 hours before you fit it. Then reset the BMS (no tools required).

Just as a follow up, I can get a battery tomorrow, before my ford appointment on Thursday. 

I'm completely new to Forscan but is it fairly straight forward to reset the systems related to the above, and will the vehicle still be driveable afterwards, or will it not function properly and need to be towed to a garage once the new battery is installed? 

I'm just worried I do something stupid 😅

FORScan is not require to reset the Battery Monitoring System (BMS). To reset it just follow either method 1 or 2 depending on the type of headlight switch you have. Make sure to be sat in the car with the drivers door closed.

On 3/29/2023 at 8:13 PM, unofix said:

How to reset the BMS method 1                                                               

 

 

On 3/29/2023 at 8:14 PM, unofix said:

How to reset the BMS method 2                                                                         Search Tag: BMS2

CAUTION: The reference at the beginning of the video saying that the BMS should be reset after charging the battery in incorrect.

The Battery Monitoring System (BMS) should only be reset if a new battery has been fitted.

 

15 minutes ago, unofix said:

FORScan is not require to reset the Battery Monitoring System (BMS). To reset it just follow either method 1 or 2 depending on the type of headlight switch you have. Make sure to be sat in the car with the drivers door closed.

 

 

That's brilliant, thanks for really quick, informative replies. 

I'm getting a Yuasa EFB096 Start/Stop Battery battery today, and I'll charge it for 12hrs and fit it early Wed morning and reset the BMS once it's fitted.

Then I'll drive it to the garage for the software updates on Thursday. 

Should I not get the diagnostic test now, they want £312 for a diagnostic 😅

2 hours ago, unofix said:

FORScan is not require to reset the Battery Monitoring System (BMS). To reset it just follow either method 1 or 2 depending on the type of headlight switch you have. Make sure to be sat in the car with the drivers door closed.

 

 

I've got the new battery charging on a 4 amp smart charger now, it's sitting at 13.4V and charging still. 

Should I just let this do its thing for another 11hrs?

The last thing I'm not sure about, is the software updates mentioned by Dave above, is this something that definitely needs done? 

Sorry I'm hopeless with this stuff haha 

£312 for a diagnostic? That is a fxxxing rip off and you are being had over.

9 minutes ago, anon said:

£312 for a diagnostic? That is a fxxxing rip off and you are being had over.

That's exactly what I thought 😂 I'd rather not have to take it there, but with work on Friday I need transport, so really hoping this works 🤞

4 hours ago, Naten576 said:

Should I just let this do its thing for another 11hrs?

Yes !!

6 hours ago, Naten576 said:

Should I not get the diagnostic test now, they want £312 for a diagnostic

No !!!!!

My cars more efficient than ever now, zero errors, stop/start still works, no info lost on radio etc and 60 miles added to my fuel range!

Ford diagnostic has been cancelled! 

Thank you to everyone who replied and helped me from a massive headache! 

51 minutes ago, Naten576 said:

stop/start still works

So sorry to hear that, but good to know everything else is fine. With a bit of luck stop/start might just cease working in a few months 😉

Don't bank on it! Mine works just fine. Regular high mileage runs and lifting off downhill keep it going. SoC factory settings and I don't even suffer from keyless entry failure.

The error has come up again today... Check brake system and Hill start assist disabled. 

Guess I need to book it into an auto electrician.. Damn.. 

2 hours ago, Naten576 said:

Guess I need to book it into an auto electrician.

.....and the battery state of charge is ?????

I'd be concerned that the alternator is not charging the battery correctly.

2 hours ago, unofix said:

.....and the battery state of charge is ?????

I'd be concerned that the alternator is not charging the battery correctly.

Yeah the batteries charge is the problem, likely the alternator as the battery is at 12.8v now and slightly dropping in idle. 

I don't think there is an alternator on an mHEV vehicle? The 12v battery is charged from the mHEV battery through a DC/DC converter I believe. No idea how to go about diagnosing faults with that system.

On 8/26/2025 at 3:53 AM, Naten576 said:

Errors found on OBD Scanner:

P0CA2 - DC/DC Converter step down Voltage Performance - internal electronic failure

This might provide a clue to where the problem lies.

Get somebody who knows what they are doing to check all the plugs and sockets  feeding into and out of the dc-dc converter. This looks like a loose connection which means that the battery is not being charged. Until then, just keep charging the battery overnight.

NB. A look around shows that this is a readily available component and I would, wearing my electronics engineer's hat, have no problem with a used item from a dismantler.  Check the Ford price first if it is needed though, some  breakers can be 'cute'.

13 hours ago, pcaouolte said:

This might provide a clue to where the problem lies.

 

9 hours ago, anon said:

NB. A look around shows that this is a readily available component and I would, wearing my electronics engineer's hat, have no problem with a used item from a dismantler.  Check the Ford price first if it is needed though, some  breakers can be 'cute'.

Thank you!

I'll see what Ford quotes, and take it from there. 

I'll update here when it's all sorted, for anyone else that may run into this problem. 

Just an update, as of today the Ford garage said that the battery drain was caused by an outdated module and they have updated it now. 

The battery is apparently no longer draining, I pick it up tonight so here's hoping. 

53 minutes ago, Naten576 said:

Ford garage said that the battery drain was caused by an outdated module

I'd like to say well done, but I don't believe them 😟