Q: Check engine light, smoke, car won't start

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Car's check engine light turned on, I took it to Autozone so that they could test the car. We got code # P0125. I checked the car's coolant level, it was pretty much inexistent so I filled it up with 50/50 coolant. The next morning some smoke started coming out of the front part of the car on the driver's side. I thought it could be that it was a cold morning so I didn't think much about it. On my way home I noticed the car's temperature had changed abruptly to the high. I stopped the car at the side of the road, waited until the car cooled down a little. I started the car again without issues. Once the smoke started coming out again I stopped the car again. This time the car would not turn on. Whenever you try to turn it on it makes a constant noise. No clicking, just a loud constant hum but it does not ignite. I checked the coolant level, maybe there was a leak, but it had the same level as yesterday. Now I'm stuck wondering how to fix it. Any help will be appreciated!!

My car has 80000 miles.
My car has an automatic transmission.

Hi there:

Sometimes the best way to diagnose a problem is to review the timeline of events. First, if your check engine light was triggered by an P-0125 OBD-II code, the issue may be a faulty ECT sensor. P0125 is the OBD-II generic code for the engine computer, or Engine Control Module (ECM), not detecting enough heat in the cooling system before the fuel management system can take control. However, if you had extremely low coolant inside the radiator, smoke from exhaust, increased temperature and no noticeable leak, and now you’re having difficulty starting the engine, it’s likely that you have internal engine damage causing coolant to leak inside the engine block or cylinder heads. The best way to diagnose this issue is first, check your engine oil. If it’s milky, then you likely have suffered serious engine damage such as a blown head gasket. This can be a very expensive repair, so you might want to consult with a professional mechanic on whether the cost to repair your vehicle is worth the expense.

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Hi there. The code you retrieved is not a diagnosis. The engine computer monitors system operations and compares the data to set specification range. When the operation falls outside the specifications the computer sets a code; it does not know what, how, or why. The codes and data lead a technician to the proper system to diagnose. Even though the coolant was low, the steam and overheating should have provided clues to discontinue vehicle operation until is was properly diagnosed. It sounds like you may have had a problem with a coolant leak that went unnoticed and you may very well have internal engine damage now. Without coolant, the engine would overheat very quickly and this leads me to believe that there has been a cooling system fault that has not had the proper attention. I suggest having a qualified technician perform inspections on the cooling system, the no start concern, and the check engine light to avoid replacing unnecessary parts. Your Mechanic has several technicians available that can assist you with a check engine light inspection, a car overheats quickly inspection, and a car does not start inspection.

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