What Causes the Car's Warning Light to Stay On After Being Flooded?
3 Answers
The reasons for the car's warning light staying on after being flooded include ECU CAN bus failure, excessive carbon buildup, and poor fuel quality in the electronic control system. Here are the details: 1. ECU CAN bus failure: Poor contact in the ECU CAN interface causes all dashboard warning lights to illuminate. 2. Excessive carbon buildup: Excessive carbon deposits in the throttle body, idle motor, and combustion chamber change the cross-sectional area of the air passage. This prevents the control unit from precisely regulating the idle air intake, resulting in an overly rich or lean fuel mixture, engine failure to start, and all dashboard warning lights illuminating. 3. Poor fuel quality in the electronic control system: Inconsistent fuel pressure maintenance and low fuel pressure in the electronic control system lead to difficulty starting the engine, causing all dashboard warning lights to illuminate.
I found that the car was flooded but the lights were still on, which is basically caused by a short circuit after the wires got wet. Water conducts electricity and will ground the circuit, causing current to continuously flow to the headlights. For example, the headlight switch or relay may get stuck when soaked, making it impossible to turn off the lights. The fuse may also blow but not completely, causing abnormal circuit connections. I've repaired many similar cars where the door locks, windows, etc., may malfunction after flooding, which is a sign of electrical system disorder. Immediately disconnect the battery's negative terminal to prevent short circuits from damaging more components. Let the car dry for a few days or use a hairdryer to dry the wiring, then take it to a professional repair shop to inspect and replace damaged parts. Never force the lights on and drive—it's too dangerous, as water residue can corrode the entire circuit and cause more problems.
Just went through the nightmare of my car being flooded, and the lights wouldn’t even turn off—totally freaked me out. I suspect water got into the wiring or switches, causing a short circuit to the ground. It’s like when a relay gets waterlogged and sticks open, or a fuse corrodes from moisture but leaves a partial connection. Other issues followed: dashboard lights flickering, windows struggling to go up and down—all signs the whole electrical system’s messed up. Safety first, so I popped the hood and disconnected the battery to prevent overheating and fires. Now waiting for the car to dry before taking it to the shop. Post-flood, the engine and computer modules need checking too—leftover moisture can cause long-term damage. Hope others learn from my mistake: avoid parking in low spots during bad weather.
