Błędy P0A8D i P2502 to nie jest słaby akumulator!

[krzychun]

Ale masz i-ELOOP czy bez? Z i-ELOOP to chyba może być dużo więcej.

Gdzie to mierzysz?

[Mazzzdacz3]

Bezpośrednio na alternatorze, masę do obudowy a plus do kabla który z niego wychodzi, po zdjęciu plastikowej zaslepki

[afm31]

First of all sorry for posting in english, but I do not speak polish and I use a translator to read this forum.

I also have the exact problems described in this thread and used data logging etc. to isolate the faulty part. And I 100% agree with you, that a faulty DC/DC converter is causing this problems. To be more specific – I think the DC/DC convert has problems switching between the different i-eloop modes and get's stuck. (maybe a problem with the bypass relais which are built in the converter)

In my car the converter DJ4V-67Y6Y-B is used. So I again agree with you – I am quite sure the "B" revision is faulty.

I am willing to investigate this topic further, and that's why I am writing this post, because this is the only forum/thread I found online which is very close to the (in my opinion) correct solution.

So are you guys still into it and do you have any news about this problem? I think the following would be very interesting questions:

– Is there a cheap replacement DC/DC convert? e.g. is DJ4V-67Y6Y-B compatibel to DAY0-67Y6Y? In the Mazda service manuals the DC/DC Converter on a CX3 is only described as "67Y6Y".

– Is it possible to open the DC/DC converter an find/replace the faulty part?

– Is it possible to "force" a fixed bypass mode by software? I already tried to (successfully) disable ieloop using FORESCAN and changing the IC configuration – but it doesn't change the faulty charging behaviour. So I guess the answer is "No".

– Is it possible to "force" a fixed bypass mode by hardware? My idea would be to disable the capacitor by unplugging/disconnecting it. Has anybody tried it?

[krzychun]

Hi!

You could try disabling the hood open sensor (it's located in the latch), which might trick the i-LOOP system into thinking the hood is always open. From what I understand, that stops it from using the capacitor. This is also a trick to turn off Start&Stop. Maybe that’ll force it into a fallback mode that works?

As for the root cause, the service suspects that some components may have come loose or shorted due to excessive heat. So if someone can get the case open, a skilled electronics technician might be able to repair it.

[afm31]

Interesting – I knew that the hood sensor interferes with i-stop/i-eloop – but from my understanding it just disables i-stop but doesn't change i-eloop behaviour. But I do not have any valid or detailed information about this.

As for the root cause, the service suspects that some components may have come loose or shorted due to excessive heat. So if someone can get the case open, a skilled electronics technician might be able to repair it.

If this is the case – and the defect is visible on the circuit board, it would be quite easy to fix. The case itself look like it should be possible to screw it open.

For those who are interested I have attached the workshop manual for i-eloop – which give very detailed insights to the system.

[krzychun]

The hood open sensor is only present in models with i-LOOP, so I’m guessing (maybe incorrectly) that it’s there as a safety feature — possibly to prevent electric shock from the high-voltage capacitor.

[wstrzalka]

Hi there – watching this thread for a few days now.
I have exactly same problem with my DJ4V-67Y6Y-B series in my CX-3 for years now. Didn't knew (nor did authorized service) what it was about. Sometimes I get failure after 5minutes of driving and sometimes it's OK for 6 months....

I would not be that fast with hood open sensor. In my car it never goes to sleep in such a case sucking over 130mA power instead of ~10mA when closed. So you replace one issue devastating you accu with another – it just don't blink on the console.

Same as afm31 I'm very interested in possible replacement ouside of DJ4V-67Y6Y-... line?
Eg. DA7A-67Y6Y is very similar but have different mount. But is it compatible? Does -E version from that series is comparable to -E version from DJ4V-67Y6Y?

Wojtek

[afm31]

Glad to hear that there are still other people out there who do not resign on that cursed i-eloop technology!

Same as afm31 I'm very interested in possible replacement ouside of DJ4V-67Y6Y-... line?
Eg. DA7A-67Y6Y is very similar but have different mount. But is it compatible? Does -E version from that series is comparable to -E version from DJ4V-67Y6Y?

I am afraid we have to stick to DJ4V-67Y6Y line – accordingly to the Mazda service manuals, there are 2 different types of DC/DC converters out there. One is a downstep converter, converting 12-25V to 12V in i-eloop cars which are equipped with the 25V capacitor.
The other one is an upstep converter converting <12V up to 12V for i-stop cars without capacitor. It is used to keep board electronics running, while the voltage drops when the car is restarted after an i-stop stop.

I assume that both types are built in likewise cases – and maybe that is the reason the complicated DJ4V is much more expensive than other 67Y6Y models.

My next step is, I am trying to get my hands on a DJ4V-67Y6Y-D model and replace my DJ4V-67Y6Y-B model.
When the car is running fine with the DJ4V-67Y6Y-D model, I will disassamble the DJ4V-67Y6Y-B and try to dig into the circuite board to maybe find a broken componente.

Dopisano 14 Aug 2025, 13:36:

On the second page of this thread a user said: (sorry for the translation to english)

A recommended person is battling it – an electronics specialist who only deals with Mazdas. He keeps insisting that the problem isn't with the part itself (the converter – meaning some cold solder joints inside) but with the control/software.

... and I too would not rule out this idea. It could also be a failure in communication caused by a corroded contact or a loose solder point.

In fact there already has been communicated such a problem by Mazda in the context of i-eloop (see the attachement)

[darrecki]

wstrzalka PM me your VIN, I'll check compatibility with higher revisions.

But in my opinion DJ4V-67Y6Y A/B/C/D are the same. When Mazda make some improvements, they always change last digit. For example, shocks for my car are rev F, all revisions looks the same and are interchangeable. Of course they behave differently.

afm31 if your car is EU/UK/Aus, i can check your VIN as well. I do not have access to american market info.

[afm31]

wstrzalka PM me your VIN, I'll check compatibility with higher revisions.

But in my opinion DJ4V-67Y6Y A/B/C/D are the same. When Mazda make some improvements, they always change last digit. For example, shocks for my car are rev F, all revisions looks the same and are interchangeable. Of course they behave differently.

afm31 if your car is EU/UK/Aus, i can check your VIN as well. I do not have access to american market info.

Thank you! I have messaged you my VIN.

I too believe that the models DJ4V-67Y6Y A/B/C/D are interchangeable without any problems.

But – DAY0-6Y6Y and DA7A-67Y6Y – they look the same – but I guess they are different models. (maybe i-stop without i-eloop?)

[darrecki]

As pictured, B to E are interchargeable. E is latest revision

[krzychun]

I would not be that fast with hood open sensor. In my car it never goes to sleep in such a case sucking over 130mA power instead of ~10mA when closed. So you replace one issue devastating you accu with another – it just don't blink on the console.

Interesting, but if this allows avoiding the problem, one could assemble a simple relay that would fake opening the hood, for example, after starting the engine...

On the other hand, we have ~2000 euros for a new converter...

[afm31]

one could assemble a simple relay that would fake opening the hood, for example, after starting the engine...

If a "hood open" signal really and reliable switches to a working bypass mode it would be easy to create a little microcontroller circuit that simulates a "hood open" if the system voltage drops below 12,1V.

Anyway – I suppose that exactly these bypass relays or the communication which activates them are faulty in our DC/DC converters. So this would not be a real solution.

Next time I notice a voltage drop below 12V (they occure very often the last weeks) I will immediately try to open the hood and check whether bypass mode is activated immediately.

[krzychun]

The bypass activates when it throws errors and then the voltage is correct.

The issue I encountered happened when the capacitor was already charged and the battery had a SoC ~ 90%. In my opinion, the problem lies in the circuitry responsible for switching the current from the capacitor to power the entire car.

[afm31]

I have definitily seen a situation in my car where SOC was <60%, capacitor was filled 100%, battery discharged till it hit 11V.
Then DTCs P2502 & P0A8D where displayed AND the battery STILL kept discharging while the capacitor remained at 100%.

I had to stop and turn ignition OFF/ON to get everything working again. That's why I do NOT trust the bypass mode in our faulty DJ4V-67Y6Y-B to be working 100% correct.

[krzychun]

I was talking about the kind of conditions that usually trigger the issue.

Every time the errors pop up, I check the voltage and it’s usually just under 15V (firstly I was using a regular OBD adapter, before I got Forscan.) with a high current – basically max charging a dead battery.

[afm31]

I have now ordered a DJ4V-67Y6Y-D – should be delivered in about a week. I will replace my model "B" with model "D" and verify if there is any reprogramming necessary. (I don't think so – I expect a plug and play job )

If the car runs fine with the model "D" I will disassamble the model "B" and investigate the circuite board.