* Coolant Leak: This is a very common cause. A leak in the radiator, hoses, water pump, or head gasket can cause coolant (which is mostly water) to drip and trigger a check engine light because the engine's computer detects low coolant levels or overheating. This is a serious problem and requires immediate attention to prevent engine damage.
* Power Steering Fluid Leak: Power steering fluid is also mostly water-based, and a leak can result in a fluid drip and a check engine light if the system's sensors detect a pressure problem or low fluid level.
* Transmission Fluid Leak (Less Likely): Though less common to trigger a check engine light directly, a significant transmission fluid leak could cause problems that indirectly lead to a light. Automatic transmission fluid contains water and can drip.
* Leaking Injector/Fuel System: A leak in the fuel injectors or fuel lines could cause fuel to mix with water and cause the check engine light to come on due to fuel mixture issues. However, fuel leaks often smell strongly.
* Condensation: While less likely to be a constant drip, condensation from the air conditioner can sometimes accumulate and drip after the car has been running, particularly in humid weather. This usually isn't related to the check engine light, though.
* Problem with the Repair: It's possible the original problem wasn't properly diagnosed or fixed. There might still be a fault in the system that the check engine light is accurately reporting.
What to Do:
1. Don't ignore it: Driving with a persistent check engine light and a leak can cause significant and costly damage.
2. Get a professional diagnosis: Take your vehicle to a qualified mechanic. They can diagnose the specific source of the leak and the reason for the check engine light. This often involves a scan of the car's onboard diagnostic (OBD) system to get the specific error codes.
3. Note the color and smell of the liquid: Is it clear (like water), green (coolant), reddish/brown (transmission fluid), or another color? Does it have a specific smell? This information is very helpful to the mechanic.
4. Note the location of the drip: This will help the mechanic pinpoint the leak's source.
In short, the combination of a check engine light and water dripping strongly suggests a leak requiring professional attention. Ignoring it could lead to major engine problems or even a breakdown.
