DS5 Hybrid4x4 - Cooling system bleed

[Crystalyne]

Hey all,

I'm looking for some information about how to bleed the cooling system on my car. Following it coming back from a service (06/2026) it's encountered various transient faults which I believe I've tracked down to being caused by an air pocket in the cooling system which is causing the car to throw all sorts of codes, however the car itself drives perfectly fine.

List of codes that I've seen:
- P0A35
- P1A79
- P1498

I've also seen these codes, but I believe these may be cascade codes caused by one of the 3 codes above:
- P1AD9
- P1AC4
- P2125

Many thanks!

[mickthemaverick]

It's helpful if you can post the definitions of the codes to save the helpers time in looking them up.

[Crystalyne]

It's helpful if you can post the definitions of the codes to save the helpers time in looking them up.

No worries, as follows:
P0A35: Drive motor 'B' overtemperature
P1A79: Drive train - Starting does not conform
P1498: Air mixer unit-Position incorrect (too closed) (After sales)

P1AD9: Drive train-Reversible alternator control fault
P1AC4: Drive train-Failure of the activation of the electromotor sub-assembly
P2125: Air mixer unit-Drift on the initialisations of one of the two stops

[French Divas]

Well, that doesn't look as a cooling liquid problem to me...
I've had a lot of cooling problems (leaking of all sorts) on my DS5, but they rarely give any fault codes.
Even if the system is practically empty, it just runs. It then gives only errors when temperature is too high.

It has 2 bleed screws. But in my experience, they can't remove all air and topping up is necessary anyway.
So the easy way:
- Fill system
- Drive 5 miles
- Top up
- All good (most of times)
- Otherwise: drive 10 miles
- Top up

[PaulC5]

If you think these codes are a result of the service I would be taking the car back to the dealer who carried it out.

[Crystalyne]

If you think these codes are a result of the service I would be taking the car back to the dealer who carried it out.

I did, the independent garage that did the service seem to think the codes are due to the car needing a "software update" that Citroen needs to do.

I'm fairly sure Citroen have long since discontinued software support for this car (I had all the software updated by Citroen when I bought the car), so I think they don't know.

Regardless, I've got the car booked to go to Citroen but I'm trying to see if I can do some work myself to try and resolve the issue as the Citroen appointment is a little while away and I could really use having the car before then.