P0794
Intermediate Shaft Speed Sensor A Circuit Intermittent
Transmission (speed sensor)
Generic OBD-II
Medium
What it means
P0794 means the intermediate shaft speed sensor A signal is dropping out intermittently. The transmission uses this sensor to compare shaft speeds and time its shifts, so a coming-and-going signal can cause occasional erratic or harsh shifting and a temporary failsafe mode. The fault most often lies in the sensor wiring or connector.
Medium
Can I keep driving? Usually drivable, but expect occasional erratic shifts or a brief limp mode; get it checked soon.
Common symptoms
What you'll notice
- Occasional erratic shifting or failure to shift
- Slipping or delayed engagement
- Transmission may briefly enter limp mode
- Check-engine light on
Common causes
Most likely first
- Loose, corroded, or damaged wiring/connector at the sensor (intermittent faults are usually wiring)Likely
- Failing intermediate shaft speed sensorCommon
- Metal debris or damage at the sensor tip or tone ringCommon
- Faulty transmission control module (rare)Less often
How to diagnose & fix
Work through it in order
- Wiggle-test the sensor harness and connector while watching the signal.
- Repair corroded or loose connections in the sensor circuit.
- Inspect the sensor tip and reluctor ring for debris or damage.
- Measure the sensor output/resistance and replace it if faulty.
- If the signal is still intermittent, evaluate the TCM.
FAQ
Quick answers
Is it safe to drive with P0794?+
Generally yes for short trips, but a dropping speed signal can cause erratic shifts and limp mode, so have it diagnosed soon.
Can I just clear P0794?+
It will return the next time the sensor signal drops out; the wiring, connector, or sensor needs repair to keep it from resetting.
Related codes
Often seen with P0794
Read & clear P0794 yourself
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✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX