P0791 – Intermediate shaft speed sensor -circuit malfunction

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By John Kershaw (Contact Me)
Last Updated 2016-01-17
Ed.D, PhD Philosophy, BSME
CodeFault LocationProbable Cause
P0791 Intermediate shaft speed sensor -circuit malfunction
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Wiring, poor connection, intermediate shaft speed sensor, ECM/PCM!TCM

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Table of Contents

  1. What Does Code P0791 Mean?
  2. What are the common causes of code P0791 ?
  3. What are the symptoms of code P0791 ?
  4. Codes Related to P0791
  5. Get Help with P0791

What Does Code P0791 Mean?

DTC P0791 sets when the PCM/TCM has received an input signal from the transmission intermediate shaft speed sensor circuit that is either irrational, erratic, or in some way incorrect. Without a usable output speed signal the transmission cannot provide a proper shift strategy

NOTE: Whenever diagnosing a 700 series DTC (Diagnostic Trouble Code) with a transmission, transfer case or other driveline components, check for a DTC under chassis and body systems, not just under “P” or powertrain/engine or emission control type codes. Module communications DTCs are “U” codes. These are most often found when looking for DTCs under chassis or body systems. Chassis related codes are labeled “C” and body system related codes are labeled “B” codes and these can cause drivetrain issues if they affect a sensor that is also used by the heating and air conditioning system.


What are the common causes of code P0791 ?

  • Defective intermediate shaft speed sensor
  • Defective output speed sensor, or input speed sensor
  • Shorted, open, corroded, or damaged wiring circuits or connectors
  • Defective shift solenoid
  • Defective engine drivability sensors, like the ECT (Engine Coolant temperature),
  • Contaminated transmission fluid that restricts flow, defective valve body
  • Defective PCM

What are the symptoms of code P0791 ?

  • MIL (Malfunction Indicator Lamp [Check Engine & Service Engine Soon])lights on with stored historical P0791
  • Harsh shift, failure to shift
  • Decrease in fuel economy
  • Speedometer may fluctuate or not work
  • Engine may stall when coming to a stop, engine misfire, sag, stall, or hesitation,
  • There may be no symptoms

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