P273F: Transmission Fluid Temperature Sensor B Over Temperature Condition
Do not keep driving
Stop somewhere safe and let it cool before driving on. If you can do so safely, leave the engine idling in neutral rather than switching off — that keeps fluid moving through the cooler and cools it faster. If you were towing or climbing, that is likely the cause; reduce the load and avoid labouring in high gear. If it happens in ordinary driving, do not keep going — have it recovered and mention the fluid cooler, which is a common and inexpensive cause.
What this code means
Transmission fluid temperature sensor B is reporting an over-temperature condition.
This is a measurement, not a circuit fault: the fluid really is too hot.
Heat is what kills automatic transmissions, and the relationship is brutally steep. Fluid life roughly halves for every 10 °C above its design temperature, so a transmission run hot for one long tow can lose a large fraction of its fluid's remaining life in an afternoon.
Three explanations, in order of how cheap they are. The cooler — blocked externally with dirt, restricted internally with debris, or bypassed by a stuck thermostatic valve. The load — towing, a long climb, heavy traffic on a hot day, or a torque converter that is not locking up and so is stirring fluid instead of driving through it. And slipping, which generates heat internally and is the one that is already causing damage.
Stopping and idling in neutral cools it faster than switching off, because the pump keeps circulating fluid through the cooler. Switching off traps the heat in the unit.
Transmission fluid is the first thing to check and the thing most often skipped.
It is not a lubricant that also happens to move things — it is the working fluid of a hydraulic machine. It carries the pressure that applies every clutch, it carries the heat away, it lubricates, and it is the friction surface itself: the additive package is tuned so clutches grip smoothly rather than snatching.
So fluid that is low, old, burnt or of the wrong specification changes how the transmission behaves, and it does so before any part has failed. Burnt fluid smells burnt and looks dark; healthy fluid is translucent. Checking it costs nothing and rules out a great deal.
"Filled for life" is a claim about the warranty, not the transmission. Many sealed units have no dipstick and a manufacturer schedule that never changes the fluid, and they still wear out faster on original fluid than on serviced fluid.
Likely causes
Start here
- Blocked or restricted transmission fluid cooler · specialist
- Towing or sustained heavy load · easy
- Low or degraded transmission fluid · moderate
- Worn transmission friction element · specialist
Less common
- Faulty transmission fluid temperature sensor · specialist
Symptoms
Components involved
Information, not instruction
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