An automatic transmission overheats when it makes more heat than its cooler can remove. The usual causes are low or worn-out fluid, towing or hauling heavy loads, long stop-and-go driving in hot weather, a clogged or undersized transmission cooler, and internal slipping, which turns engine power into heat. Heat is the main cause of automatic transmission failure, so treat a warning seriously.
Symptoms of transmission overheating
- A transmission temperature warning light or message
- A burning smell; see burning smell from car
- Slipping, delayed or harsh shifts; see transmission slipping
- Dark or burnt-smelling fluid; see transmission fluid color
- Limp mode with the transmission held in one gear; see limp mode
Causes
| Cause | Why it adds heat |
|---|---|
| Low fluid | Less fluid to carry heat away; check for a transmission fluid leak |
| Old fluid | Worn fluid loses friction and cooling properties; see how often to change transmission fluid |
| Towing and hauling | Higher torque converter slip and load |
| Clogged or small cooler | Heat cannot leave the fluid; see transmission cooler |
| Internal slipping or a failing torque converter | Friction turns power into heat; see torque converter symptoms |
| Engine cooling problems | Many coolers sit in the radiator, so an overheating engine heats the transmission too |
What to do if the warning comes on
- Slow down and reduce load. If you are towing, pull over when safe.
- Follow your owner’s manual. Many recommend stopping, placing the transmission in park and letting the engine idle so fluid circulates through the cooler.
- If the warning stays on, shut the engine off and let it cool.
- Check the fluid level and condition once cool; see how to check transmission fluid.
How hot is too hot?
Normal operating temperature for most automatic transmissions sits well below the temperatures reached when towing heavy loads up long grades. Fluid life drops quickly as temperature climbs, which is why manufacturers specify shorter fluid intervals for towing. Check the range your manufacturer gives and compare it with a gauge reading during your usual driving; see transmission fluid temperature for typical figures.
Overheating warning with no towing
If the warning appears in ordinary driving, suspect low fluid, a blocked cooler, a failed engine cooling fan or internal slipping rather than load. Get it checked before the next long trip.
Preventing overheating
- Change fluid on the severe service schedule if you tow; see flush vs change.
- Add an auxiliary cooler for heavy towing.
- Use tow/haul mode where fitted, and a lower gear on long grades.
- Watch transmission temperature on a gauge or scan tool; see transmission fluid temperature.
After an overheat
One brief overheat may cause no lasting harm, but burnt fluid, slipping or new noises suggest damage. If it fails, compare a rebuild with our replacement transmissions.
Trouble codes: P0711 Trans Fluid Temp Sensor Range · P0700 Transmission Control System · P0741 Torque Converter Clutch Stuck Off · all OBD2 codes.
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