p1a12 fault

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Oct 20, 2023
I would like to ask for help, I have read through many posts and comments on the forum, but I can't find a solution to my problem.
I bought a C-zero m.y. 2011, trouble is that the car does not charge.
When I read out the faults with Diagbox, I found fault P0A09, not charging the 12V battery.
I took the OBC cover off (disconnecting the current first, as I should), then found 3 parts that blew, the usual 2pcs ceramic capacitors (1nF 3kV dc S3N) and a piece of polypropylene capacitor (2.2uF 310V ac). I soldered the ones in the brackets to replace the bad ones.
I replaced the fuse in the right unit.
I cleared the faults.
The car started and charged the 12V battery with 14.5V.
Much to my delight, but, when I went to charge the car at 230V, charging started, fan whirred then the yellow little car with the exclamation mark appeared on the dashboard and stopped charging.
After a fault reading P1A12 appeared in the EV Ecu.
I checked the wiring, disconnected the air conditioner and water heater connections but the fault persisted.
I'm at a loss, stuck trying to find the fault, I spoke to a friend who has repaired cars with this fault but hasn't come across this yet.
Thanks in advance.
Howdy and welcome to the forum, sorry to hear of your troubles.
The P1A12 DTC is a high level code to cover any fault except 26 and 32 in the list of OBC codes, which can be found at the last post of page 1 of the OBC Troubleshooting thread, see here

Unfortunately we haven't figured out a way to read the OBC number codes without a MUT or the equivalent Renault/CZ tool.

Most OBC failures are typically on the HV DC output side (snubber caps that you replace), or on the AC Input side (AC caps, ceramic precharge resistors, AC relay).

Many times when the snubber caps fail, they explode and eject hot molten metal throughout the local area to hit the bottom of the control board, creating short circuits and secondary damage, so inspect carefully for metal splatter.

The FSM page for this code:
Thank you for your reply, I will take the top plate out and check if there is any damage.
Is it difficult to replace the old type OBC with the newer type?

I have the same faultcode with one of my cars. And try to find out how to fix it. Did you already did it?

And replacing the OBC V110 with the newer Version V100 is simple. You need to make a few changes with the old plugs on the new one, but it should be no Problem.