Q: Alt temp light?

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My alt temp light is on, what does that mean?
My car has an automatic transmission.

Assuming you are referring to the AT temp light, this is related to your transmission and indicates that the transmission may be overheating. The ideal transmission fluid temperature is under 175 degrees, but as fluid ages it starts to break down and lose its capacity to cool down the transmission. This is when transmission overheating occurs. At 220 degrees, varnish forms. At 240 degrees, seals start to harden. At 260 degrees, you’ll often experience transmission slipping as plates slip. At 295 degrees, seals and clutches start to burn and fluid forms carbon, at which point transmission failure might happen soon. I would suggest having a professional from YourMechanic come to your location to take a look at your vehicle to determine what may be causing this.

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