Water infiltration in the fuel injection module via the windshield washer nozzle (Citroën C3)

There is a chronic design flaw in the first and second generation C3. Water from the windshield washer nozzles or rainwater running down the hood can leak through the washer hose.

• The Real Problem (Siphon Effect): The windshield washer hose runs directly above the connectors of Fuel Injection Module (ECU). If the seal on the hood washer dries out or the hose cracks, water drips onto the wires and, through capillary action, runs through the wiring harness until it reaches the module pins.
• The Consequence: Water causes oxidation (verdigris) on the module pins and connectors. This leads to short circuits, ignition failures, and, in severe cases, complete ECU failure.

Location of Protection (Fuses): When this short circuit occurs, the engine management system’s protective fuse blows. BSM (under the hood):

• Correct Fuse: It’s the fuse. F10 or F15 (15A). If it burns out, the car “dies” and won’t start because the fuel pump and coils stop receiving power.

How to Prevent It:

1. Sealing the Nozzles: Apply a thin layer of neutral silicone to the base of the washer nozzles on the hood.
2. Deflect the Whip: A common solution in specialized workshops is to create a downward “curve” in the module’s wires (a “drip channel”), so that if water runs down the wire, it falls to the ground before reaching the connector.