The intermediate shaft speed sensor measures a shaft between input and output – a countershaft on Toyota's U760 six-speed, the intermediate shaft behind the overdrive set on Ford's 5R110W. Together with turbine and output speed it lets the module check each gear stage and control clutch slip. Ford uses P0791 as its only intermediate shaft code, for 'no or too little signal': while the vehicle drives under power (turbine at least 1500 rpm, output at least 650 rpm or 15 mph), the sensor reports below 250 rpm for 5 s – in the 2012 and 2020–23 summaries, with MIL. A Toyota bulletin for the U760 (Highlander, Venza, Camry 2009–10) replaces the countershaft sensor for P0791/P0793. GM's 10-speed has two such sensors but uses its own codes. Limp mode and harsh shifts follow.
Medium severity. Can I keep driving?Drive gently to a repair shop. If it slips, you hear clunks, or it loses its gears, do not keep driving.
Symptoms
- Check engine light
- Limp mode or fixed gear
- Harsh or delayed shifts
- Follow-up pressure control codes (Toyota)
Most likely causes
- Intermediate shaft speed sensor faulty
- Connector or wire at the transmission (oil, corrosion, chafing)
- Reluctor wheel damaged or debris on the sensor
- Control module
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
- It can trigger limp mode.
- It affects emissions.
What each character of P0791 means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 7: Transmission
- 91: Specific fault in that system
Frequently asked questions
Can I keep driving with code P0791?
Drive gently to a repair shop. If it slips, you hear clunks, or it loses its gears, do not keep driving.
What causes code P0791?
The most common causes are: intermediate shaft speed sensor faulty; connector or wire at the transmission (oil, corrosion, chafing); reluctor wheel damaged or debris on the sensor.
Related codes
- P0792Intermediate Shaft Speed Sensor A Circuit Range/Performance
- P0793Intermediate Shaft Speed Sensor A Circuit No Signal
- P0794Intermediate Shaft Speed Sensor A Circuit Intermittent
- P0715Input/Turbine Shaft Speed Sensor A Circuit
- P0720Output Shaft Speed Sensor Circuit
- P0796Pressure Control Solenoid C Performance/Stuck Off
Sources
- newtonnet.co.uk: fordobd2012
- fordservicecontent.com: OBD Operations Summary Gasoline 2020 2023
- media.fixed-ops.com: sb0116t10
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.