Here's why:
* Low Coolant: This indicates a loss of coolant from the system.
* White Smoke: White smoke from the exhaust is a classic symptom of coolant leaking into the combustion chambers. Coolant (water) turns to steam when it's heated in the engine, producing the white smoke.
* Check Engine Light: The computer detects a problem, and the head gasket leak will trigger this light due to various potential consequences (like misfires from diluted engine oil or oxygen sensor issues from the leaked coolant).
Other, less likely possibilities (but still requiring immediate attention):
* Cracked engine block or cylinder head: This is a more severe problem than a head gasket leak, but shares similar symptoms.
* Coolant leak elsewhere in the system: While less likely to cause white exhaust smoke, a significant leak could lead to low coolant and trigger the check engine light due to overheating or related issues.
What you should NOT do:
* Do not continue driving the car. Driving with a head gasket leak can cause severe and costly engine damage. The engine could overheat, seize up, or suffer catastrophic failure.
What you SHOULD do:
* Have the car towed to a qualified mechanic immediately. Do not attempt to drive it further.
* Describe the symptoms clearly to the mechanic. This will help them diagnose the problem accurately. Mention all three: low coolant light, check engine light, and white exhaust smoke.
The repair for a head gasket leak can be expensive, potentially involving a complete engine rebuild or replacement in worst-case scenarios. Getting it checked promptly will minimize potential further damage.
