What it means
The transmission control module detects no signal from the intermediate shaft speed sensor A circuit when a signal is expected.
At a glance
- Usually lights the check-engine light
How it works
Intermediate shaft speed sensor A reports how fast that shaft is turning so the transmission control module (TCM) can compare shaft speeds and manage shifts. P0793 sets when the TCM expects a usable signal from sensor A but receives none, which can leave it unable to confirm the transmission’s speed relationship.
Common causes
Most likely first.
- Failed sensor element (open)
- Damaged reluctor wheel
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
How to diagnose it
- Check scan-tool freeze-frame data and live transmission speed readings to see when sensor A stopped reporting and whether related shaft speeds are present.
- Inspect sensor A and its connector for damage, contamination, a loose fit, or wiring that could interrupt the signal.
- Check the sensor A circuit and connector terminals for an open or poor connection, following the vehicle wiring diagram.
- Test sensor A and its circuit using the manufacturer's procedure to determine whether the sensor element is open or the fault lies in the wiring.
- If the circuit and sensor pass, inspect the intermediate shaft reluctor wheel for damage that could prevent sensor A from detecting rotation.
Common fixes
- Reconnect or repair a loose or damaged sensor A connector.
- Repair an open or damaged section of the sensor A wiring.
- Replace intermediate shaft speed sensor A if testing confirms its element is open.
- Repair or replace the damaged intermediate shaft reluctor wheel.
Can I keep driving?
Avoid towing, hard acceleration, and long trips if shifts are harsh, delayed, or slipping; the transmission may enter a protective gear or lose reliable shift control. Stop driving if it cannot engage gears safely, since continued slipping can worsen transmission damage.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.