The intermediate shaft inside your transmission will spin gradually faster until it’s time to change gears. Intermediate shaft speed sensors monitor how fast the shaft is spinning, so the ECU can know it’s time to change gears. If there is no signal coming from the ISS sensor, the ECU will log a P2751 DTC.
How Serious is the Code?
If the computer does not know when it’s time to shift gears, the safety and performance of your vehicle will be drastically affected. A P2751 diagnostic trouble code generally means that you will experience a number of transmission problems including delayed shifts, hard shifts, engine hesitation and engine stalling.
Symptoms of a P2751 include:
- Harsh, erratic or delayed shifts
- Transmission unable to change gears
- Engine misfire
- Hesitation when accelerating
- Engine stalls
- Speedometer may appear broken
- Limp Mode
- Failed intermediate shaft speed sensor
- Malfunctioning transmission input speed sensor
- Faulty output speed sensor
- Broken, loose or corroded connectors
- Frayed or shorted wiring
- Valve body or pressure related issues
- Broken shift solenoid(s)
- Defective engine temperature sensor
How to Diagnose the Code?
For a mechanic to properly diagnose a P2751 OBD2 trouble code, they should start by checking the level and condition of the transmission fluid. They will also need to inspect the wiring and connectors on the transmission wiring harness. Manufacturer TSB’s should also be looked at, to see if there are any known solutions for this problem. Should no problems be found, the intermediate shaft speed speed sensor/ISS sensor will need to be tested. The output speed sensor, input speed sensor, engine temperature sensor and shift solenoids may also need to be inspected.
What Repairs Will Fix P2751?
- Replace intermediate shaft speed sensor
- Replace output speed sensor
- Replace input speed sensor
- Repair or replace damaged wiring and/or connectors
- Replace the engine temperature sensor
- Change transmission fluid and filter
- Flush transmission fluid
- Fix transmission fluid leaks
- Reprogram ECU/TCM
- P2745 – Intermediate Shaft Speed Sensor B Circ
- P2746 – Intermediate Shaft Speed Sensor B Circ Range/Performance
- P2747 – Intermediate Shaft Speed Sensor B Circ No Signal
- P2748 – Intermediate Shaft Speed Sensor B Circ Intermittent
- P2749 – Intermediate Shaft Speed Sensor C Circ
- P2750 – Intermediate Shaft Speed Sensor C Circ Range/Performance
- P2752 – Intermediate Shaft Speed Sensor C Circ Intermittent