P0793 means the Powertrain Control Module (PCM) is not receiving a signal from the intermediate‑shaft speed sensor, which monitors the rotation speed of the transmission’s intermediate shaft. The sensor supplies data used for shift scheduling, torque‑converter lock‑up and the speedometer. When the circuit shows no signal, the PCM sets a fail‑safe (limp‑in) mode.
The sensor itself is the most common failure; internal electronics can quit, producing no output.
An open, short, or corroded connection in the sensor circuit will prevent the signal from reaching the PCM.
The toothed wheel on the intermediate shaft can be broken or missing teeth, causing the sensor to see no pulses.
Low system voltage, a weak battery, or bad grounds can starve the sensor of the 5 V reference it needs.
Only after all sensor, wiring, and reluctor issues are ruled out should the PCM be considered as the cause.
No. The sensor, wiring, or reluctor wheel is the cause in the vast majority of cases. PCM replacement is rarely needed and should be considered only after all other sources are eliminated.
The vehicle will likely enter limp‑in‑mode, which limits performance and can cause harsh shifting. It is possible to drive short distances, but the problem should be diagnosed and repaired promptly to avoid further transmission stress.
A new sensor will resolve the issue if the original sensor has failed. However, if the wiring, connector, or reluctor ring is damaged, the code will persist even with a new sensor.
Loose or corroded connectors, broken wires, or a damaged tone wheel can create intermittent opens that cause the signal to drop out under vibration or temperature changes.