What it means
Intermediate shaft speed sensor A signal jumps or drops out — vibration, loose connector or oil mist on the sensor tip.
At a glance
- Usually lights the check-engine light
How it works
Intermediate shaft speed sensor A sends the TCM a signal that tracks the shaft's rotation during transmission operation. P0794 sets when that signal comes and goes, so the TCM intermittently loses the speed information it uses to control shifts.
Common causes
Most likely first.
- Loose connector
- Connector with intermittent contact under vibration
- Harness routed against vibrating component
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
- Review freeze-frame data and graph sensor A's live speed reading during a cautious road test to identify when it drops out, such as over bumps or during shifts.
- Inspect sensor A's connector for looseness, corrosion, oil contamination, or terminals that may lose contact under vibration.
- Follow the sensor A harness and check for rubbing, pinching, or contact with a vibrating or hot component.
- With live data displayed, gently move accessible sections of the harness and connector to see whether the sensor A reading cuts out.
- If the connection and routing look sound, test sensor A and its wiring for intermittent continuity or signal loss using the manufacturer's procedure.
Common fixes
- Secure the sensor A connector and correct loose terminal contact.
- Clean or repair contaminated or damaged connector terminals.
- Reroute and secure the sensor A harness away from rubbing or vibrating components.
- Repair damaged wiring or replace sensor A if testing confirms an intermittent sensor fault.
Can I keep driving?
Limit driving if the signal dropout causes slipping, missed shifts, or harsh engagement, and avoid heavy loads or long journeys. If the transmission loses drive or shifts unpredictably, stop safely; repeated slip can damage internal parts.
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.