P2751 Intermediate Shaft Speed Sensor C Circuit No Signal
OBD-II Trouble Code Technical Description
Intermediate Shaft Speed Sensor C Circuit No Signal
What does that mean?
This is a generic diagnostic trouble code (DTC) that typically applies to OBD-II vehicles with automatic transmissions. That may include but is not limited to vehicles from Mazda, Toyota, Chrysler, Ford, VW, Dodge, Jeep, Mercedes, Lexus, Chevrolet, etc.
Although generic, the exact repair steps may vary depending on year, make, model and powertrain configuration.
The intermediate shaft, otherwise known as the layshaft aids in distributing rotational force from the input drive to the output shaft inside the transmission. The speed of the intermediate shaft depends on which gear you are in. In a manual transmission, the gear selector dictates this, so there is no need to monitor speed of the intermediate shaft.
On the other hand, in an automatic transmission, if you are in "D" drive, the gear you are in is determined by the TCM (Transmission Control Module) using multiple sensor inputs that all contribute to the vehicle shifting smoothly and efficiently. One of the sensors included here is the Intermediate shaft speed sensor. The TCM needs this specific input to aid in determining and adjusting hydraulic pressures, shift points and patterns. Experience in diagnosing other types of speed sensors (e.g.: VSS (Vehicle speed sensor), ESS (Engine Speed Sensor), etc.) will help you here as most speed sensors are similar in design.
The ECM (Engine Control Module) in conjunction with the TCM (Transmission Control Module) may activate P2751 and associated codes (P2749, P2750, P2752) when they monitor a fault within the intermediate shaft speed sensor or it's circuits. Sometimes when the sensor fails, the TCM uses other speed sensors within the transmission and determines a "backup" hydraulic pressure in order to keep the automatic transmission functional but this may vary significantly between manufacturers.
The code P2751 Intermediate Shaft Speed Sensor C Circuit No Signal is set by the ECM (engine control module) and/or the TCM (transmission control module) when it/they detect an absent signal from the C speed sensor or it's circuit. Refer to a vehicle specific repair manual to determine which is the "C" part of the circuit for your particular application.
NOTE: Record any codes active in other systems if multiple warning lights are illuminated (e.g.: Traction control, ABS, VSC, etc.).
Photo of a transmission speed sensor:
What is the severity of this DTC?
I would say this fault is moderately severe. Like mentioned earlier, your automatic transmission may still be functioning OK. That said, it could also be indicative if one or more bigger more pressing issues. Diagnosing any transmission issue ASAP is the best strategy.
What are some of the symptoms of the code?
Symptoms of a P2751 trouble code may include:
Hard shifting Numerous instrument panel lights illuminated Poor driveability Erratic engine speedWhat are some of the common causes of the code?
Causes for this P2751 engine code may include:
Defective or damaged Intermediate shaft speed sensor Electrical fault in the wires between the speed sensor and modules used Internal ECM and/or TCM issue Other related sensors/solenoids damaged or defective (e.g.: Input shaft speed sensor, Output shaft sensor, Shift solenoid etc.) Dirty or low automatic transmission fluid (ATF)What are some P2751 troubleshooting steps?
Basic Step #1
If you're researching this code I am going to assume you have already checked the transmission fluid level. If not, start with this. Make sure the fluid is clean and adequately filled. Once everything fluid-wise is good, you need to locate the intermediate shaft speed sensor. Often tim
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