* Ignition System: Water can short out the ignition system components, including the distributor cap, rotor, ignition coil, spark plug wires, and even the ignition module. If water gets into these components, it can disrupt the electrical flow needed to create the spark that ignites the fuel-air mixture.
* Electrical Connections: Water can corrode or damage electrical connections throughout the engine bay. These connections control various systems, including the fuel injectors, starter motor, and computer. Even a small amount of water can cause a bad connection, preventing the car from starting.
* Sensors: Many sensors in the engine bay are sensitive to moisture. Water can interfere with their operation, leading to incorrect readings sent to the engine control unit (ECU), which may prevent the engine from starting. The mass airflow sensor (MAF) and crankshaft position sensor (CKP) are particularly vulnerable.
* Alternator/Battery: While less common, water can damage the alternator or even the battery terminals, preventing the battery from supplying the necessary power to crank the engine.
* Computer (ECU): Although protected, the ECU can be vulnerable to water damage, especially if water seeps into it through seals or openings. Damage to the ECU can cause a range of problems, including failure to start.
Important Note: It's generally not recommended to pressure wash an engine. A gentle hand wash with a mild detergent and a hose is sufficient. Using high-pressure water can force water into places it shouldn't be, increasing the risk of the problems listed above. If you do wash your engine, make sure to let it completely dry before attempting to start the vehicle. You should also pay attention to the electrical components and ensure they are as dry as possible.
