Citroen C4 battery error, even after replacing it with a new one

[benniemin]

Recently my Citroën C4 PureTech 1.2 started having a strange problem. If the car has been standing for a few hours and I try to start it, it won't start.

First, the doors don't open when I unlock them with the key. The mirrors also don't fold out. After I insert the key in the ignition and turn it, the car doesn't start. I get a message on the navigation screen that there are battery problems and that I should check the fog lights. If I remove the key, insert it again and try once more, the car does start. After that the car runs fine and I don't get any error messages, but the service light stays on. It then goes away by itself after a while. If I first disconnect the positive terminal and reconnect it before starting, everything is also fine and the car starts right away without any errors. Very weird!

I thought the battery was the problem. I measured the voltage and it was about 11.5 V after a night of standing (not measured directly at the battery terminals). Once the car is started the voltage almost immediately rises. If I turn the car off and measure again, the voltage is well over 12.5 V. Because of this behavior I thought the battery was slowly discharging.

After I installed a new battery today the problem remained the same. Because the old battery was disconnected anyway, I measured directly at the terminals and, lo and behold, it was above 12.5 V, so no problem with the battery.

I've also connected an OBD reader at different times, but it doesn't show any fault codes. I'm not sure where to look next. Does anyone have a tip or an idea?


Click for larger

[mickthemaverick]

The first thing I'd suggest is to do a BSI reset following the procedure in the link below, then see how it looks and report back.
viewtopic.php?p=601679#p601679

[RichardW]

It needs a new BPGA (battery protection unit) - this is a common problem - the mirrors not folding out, no response to the key, and random fog light warnings are classic signs.

[benniemin]

@mickthemaverick: Thanks for the advice! I've just done a BSI-reset, and the faults are gone. I actually get the same result (no more errors) when I just pop off the positive terminal on the battery and reconnect it. The faults will come back a couple of hours later. So I'll leave the car for a bit and check on it later. I've also scanned the car with the OBD-scanner before doing the BSI reset. No errors on the BSI where found which leaves me wonder if the issue comes from the BSI:


Click for larger

@RichardW: Thanks for the reply, I really appreciate it! I'm highly on doubt the BPGA is faulty. Because when I disconnect the positive lead for a while, reconnect it and start the car, all errors are gone. Also, I've never got a OBD-error B1624 (which should be the BPGA unit). I already bought a new battery unnecessarily, so I want to be very sure before buying a new BPGA. What makes you so sure its the BPGA?

This may be a far stretch, but a week before this problem started, I did some work on the strut top mounts. When re-assembling the car, I've noticed a gap between the windshield and the plastic/rubber (weatherstrip?) underneath it. I don't know if that was the case before, but I can imagine water now getting in places where it should not go. Could this be a problem, or is the engine/electronics compartment not connected?


Click for larger


Click for larger

[benniemin]

After some more testing and researching I'm now also thinking it's the BPGA. Thanks for pointing me to that, @RichardW!

I'm currently looking for a replacement and see that the main part nummer is 6500JE. On my car, the exact partnummer is 9805119280, which is also noted as G04. On several sites that sell these units, they state that there interchangeable, so I could also buy a 9811475080 G11 unit which would work on my 2016 Citroen C4. Is this actually true? It would save me a lot of searching for the exact partnummer. Also, is the G11 newer, or is that only a number that means nothing else?

[benniemin]

I’ve replaced the BPGA unit (went from a G04 model to a G11) and the problem has been solved. Thanks for the help, everyone!