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Technical Description of OBD-II Trouble Code
Circuit for Input/Turbine Speed Sensor “A”
What is the meaning of this code?
This diagnostic trouble code (DTC) is a generic powertrain code that is applicable to all vehicles manufactured from 1996 onwards (Ford, Honda, Mazda, Mercedes, VW, etc.).
Although it is a generic code, the specific repair steps may vary depending on the make and model of the vehicle.
Whenever I have come across a diagnostic trouble code P2765, it has been because the powertrain control module (PCM) has detected a malfunction in the circuit for the designated input (or turbine) speed sensor known as “B”. Input and turbine speed sensors have almost identical designs, with the primary difference being the descriptive terminology. The designation “A” is typically used for OBD-II equipped vehicles that utilize multiple input or turbine speed sensors. To locate the input/turbine sensor designated as A, refer to the manufacturer’s service manual.
The input/turbine speed sensor is typically an electromagnetic, 3-wire sensor that is used to monitor the transmission’s input speed, which is recognized by the PCM as revolutions per minute (RPMs). The sensor is positioned near the rear of the torque converter, either mounted with a bolt/stud or threaded directly into the transmission case.
On the transmission’s main (or input) shaft, there are specially designed grooves (or a notched reluctor wheel). The input shaft (or reluctor wheel) passes close to the end of the sensor, completing the electromagnetic circuit. As the grooves (or notches) pass by the sensor, the circuit is interrupted and an electronic pattern is formed. The PCM receives this pattern formation as a waveform pattern, which it further interprets as the transmission’s input/turbine speed.
The transmission’s input/turbine speed is compared with the engine’s RPM speed, percentage of engine load, transmission output speed, and vehicle speed to determine the desired input speed RPM. If the actual input/turbine speed does not match the desired input/turbine speed, a code will be stored and a malfunction lamp may illuminate.
Symptoms & Severity
In some cases, the storage of this code will cause the PCM to activate the transmission’s “limp-in” mode. In this mode, the transmission will shift harshly. If you encounter a P2765 code and notice irregular shifting of the transmission, it is crucial to address the problem as soon as possible.
Symptoms of a P2765 code may include:
Causes
Possible causes for the occurrence of this code are:
Diagnostic and Repair Procedures
It is always advisable to start by checking for any technical service bulletins (TSB) specific to your vehicle. Your issue may be a known problem with a known solution provided by the manufacturer, which can save you time and money during the diagnosis process.
For diagnosing the P2765 code, you will need a suitable diagnostic scanner, a digital volt/ohmmeter (DVOM), a system wiring diagram, and possibly an oscilloscope.
Skilled technicians usually begin by visually inspecting the system’s wiring and connectors. Repair or replace any disconnected, corroded, burnt, or shorted parts as necessary. Test the battery and inspect the battery cables and cable ends. Clean off any corrosion and secure the battery terminals as needed.
Connect the scanner to the diagnostic port and retrieve all stored codes. Make a note of all stored codes for future reference. If available, also note the freeze frame data.
If both input sensor and output sensor codes are present, use the scanner’s data stream to determine which circuit is malfunctioning. Narrow down the data stream to include only relevant data for more efficient data delivery.
When removing sensors, check for excessive metal debris on the magnetic contacts. Remove any excessive debris before reinstalling the sensors. When the sensors are removed, inspect the interruption grooves and/or reluctor wheel notches. Test each sensor individually using the DVOM and follow the manufacturer’s specifications (found in the service manual or through All Data). Replace any sensors that do not comply with the specifications.
Before testing the resistance and continuity with the DVOM, disconnect any related controllers. Failure to do so could result in damage to the controllers. Test the system circuits for any shorted or open wiring. Repair or replace any defective circuits. If all system circuits and sensors are functioning properly, suspect a faulty PCM or a PCM programming error.
Additional diagnostic notes:
Professional Service
While we always recommend seeking professional mechanical assistance to resolve this issue, if for some reason that is not possible, we offer the option to permanently delete this specific DTC. All other codes will continue to function normally. If you are interested in this option, please upload your ECU file to our portal.
