Transmission slipping

Common causes

1. Low fluidA leak at a pan gasket, seal or cooler line lets the level drop until the pump draws air and pressure falls. The fix can be as small as a seal and a refill.
2. Old or burnt fluidFluid that is dark and smells burnt has lost the friction properties the clutches rely on. It is also a sign the transmission has been running hot.
3. Worn clutch packs or bandsThe friction material inside an automatic wears with miles and heat. When it is thin, the clutches cannot hold under load. This is internal wear and usually means an overhaul.
4. Pressure control or shift solenoid faultsElectronic transmissions use solenoids to set line pressure and select gears. A weak solenoid or a wiring fault can cause slipping and usually stores a code such as P0730 or P0750.
5. Torque converter problemsA converter clutch that does not lock up can feel like a slip at highway speed, often with a shudder.

Slipping usually starts small: a flare in RPM on the 2-3 shift, a lazy take-off from a stop, or a gear that lets go on a hill. Drivers often notice it first in summer, when the fluid runs hottest; Reno's normal July high is 93.9 F (NOAA).

What the mechanic checks first

The shop starts with the simple things: fluid level and condition, leaks, and any stored codes. Then a road test to feel where it slips, cold and warm. Only when those point inside the transmission does a rebuild come up. In the shop's words, "We will diagnose the situation to determine the kind of service you need."

Slipping in a manual transmission

In a car with a clutch pedal, slipping usually means the clutch itself: the engine revs climb when you accelerate in a high gear, often with a burning smell. See clutch slipping or grabbing.

Can I keep driving it?

Short, gentle trips only, and call first; heavy loads, towing and long climbs are out. If it slips in every gear, will not move, or smells burnt, stop and plan a tow. The driving with a slipping transmission guide goes into more detail.