Water Damage in Engine Fuse Box

I will need to replace the engine fuse box as water has somehow entered one of the connectors and corroded the contacts on the fuse board.
I will probably have to replace the main harness as the pins from the fuse board are corroded in the connector sockets.
Has anyone else had this problem? Any ideas where the water came from as the fuse box is well sealed?

kzngmy wrote:I will need to replace the engine fuse box as water has somehow entered one of the connectors and corroded the contacts on the fuse board.
I will probably have to replace the main harness as the pins from the fuse board are corroded in the connector sockets.
Has anyone else had this problem? Any ideas where the water came from as the fuse box is well sealed?

Hi kzngmy

I don't recall this ever being mentioned before

As you say the BSM - engine bay fuse box is quite well sealed against splashes.

The BSM is not coded to the car, but there are several different versions, so matching up the same model will help, but some old C4 BSM models fit the older C3, this may also help for later versions like yours.

There are plenty of potential BSM - engine bay fuse boxes here - on eBay

The BSM next to the battery, well covered (2002), it needs a 2012 picture really



The BSM out of the car, from a 2002 model

hello there,

this is caused by the washer pump and/or washer tube splitting. it happened on my husbands car - in apr 2014, the only time he knew there was a problem, was when his lights stopped working. (he has a 10 plate) it has now happened to mine (61 plate). It cost my husband close to £1500 and Im looking at a bill around the same amount. The connectors have corroded and now I have to replace the harness.

I have spoken to Citroen, who said it is not a know issue and have offered a 'goodwill' of 20%. im furious as there is no way of knowing this happens as no checks are made during any service

melf wrote:hello there,

this is caused by the washer pump and/or washer tube splitting. it happened on my husbands car - in apr 2014, the only time he knew there was a problem, was when his lights stopped working. (he has a 10 plate) it has now happened to mine (61 plate). It cost my husband close to £1500 and Im looking at a bill around the same amount. The connectors have corroded and now I have to replace the harness.

I have spoken to Citroen, who said it is not a know issue and have offered a 'goodwill' of 20%. im furious as there is no way of knowing this happens as no checks are made during any service

Hi melf. Thanks for the information.

If its not a known issue, I wouldn't expect any checks to be done at the service. But hopefully other owners will now ask their mechanic to check for them since you have brought up the problem of the screen wash water affecting the BSI on the C3 models.

sadly it seems it is a very much known issues across all models and Peugeots too

https://www.roadtestreports.co.uk/qanda/65463

melf wrote:sadly it seems it is a very much known issues across all models and Peugeots too

https://www.roadtestreports.co.uk/qanda/65463

There's a suggestion that Citroen have replied to official complaints to this issue by claiming it's all down to the windscreen washer bottle freezing and causing a micro-crack in the electrical plug to its motor. Guess what happens then? Yep, you power up the washers and this sends the leaking water up the electrical cable and all the way to the fuse box on the other side of the engine. Ergo, it ain't THEIR fault - it's down to owners not using enough anti-freeze in their wash.

If this is the reason for water entering the fuse box from the washer pump along the wiring (which it probably is from all that anecdotal evidence in your link) then the prevention is a simple one of adding sufficient Winter Screenwash (cheap here on eBay) to stop the pump freezing.

well, I owned the old shape C3..... the one which blew fuses when the washer bottle froze in the winter..... so since then I have ALWAYS made sure that i use double strength washer solution. Just so the fuses didnt blow! and so does hubby in his car. so i cant agree with the cause! and if that is the reason, why doesnt it happen with other manufacturers?

melf wrote:well, I owned the old shape C3..... the one which blew fuses when the washer bottle froze in the winter..... so since then I have ALWAYS made sure that i use double strength washer solution. Just so the fuses didnt blow! and so does hubby in his car. so i cant agree with the cause! and if that is the reason, why doesnt it happen with other manufacturers?

I know of other manufactures cars that blow fuses with frozen washer bottles but I have not seen any that leak washer fluid into a fuse box.

If you could identify the pin numbers and the colour and location of the plug that gets damaged, it may be possible to trace the wire back on a diagram to its source. If its the washer pump, this could well be the cause.

It reminds me of the one where the coolant temperature sensor would fail and leak coolant all the way back into the engine ECU doing damage.

When you pull the ECU plug, it looked like this