NHTSA Complaint #11603978 — 2016 MAZDA CX-5

My daughter was driving her 2016 CX5 when the coolant temperature warning message displayed on the instrument panel, advising her to pull over immediately. She had just driven on to the expressway, but luckily was still in the right lane and was able to pull over safely. If she had been in any other lane of the busy highway when this occurred it could have been a serious safety issue for my daughter and the other drivers on the highway. I contacted AAA to tow the car to my local mechanic. The service tech reported that they began by plugging their diagnostic tool into the car and they received two engine codes: P111A-00 and P011A, and that a software update must be performed first. I had the car towed to Turnersville Mazda. They said that there would be a $215 per hour diagnostic fee. They found that the thermostat needed to be replaced as it failed to open during engine operation. This service incurred a $397.55 cost. After replacing it they noticed that a milky substance was produced, indicating motor oil mixing with coolant. They recommended replacing the engine due to a crack in the cylinder head at a cost of $10,300. For some reason the service tech elected to replace the spark plugs and update the software AFTER the catastrophic engine issue was discovered, incurring an additional $330 in charges. Prior to this incident there were no issues with the vehicle, no warning lamps or symptoms of any kind.