P0793: Intermediate Shaft Speed Sensor A Circuit No Signal

What does P0793 mean?

The intermediate shaft speed sensor measures a shaft between input and output – a countershaft on Toyota's U760 six-speed, the intermediate shaft behind the overdrive set on Ford's 5R110W. Together with turbine and output speed it lets the module check each gear stage and control clutch slip. P0793 means there is no pulse signal from the intermediate shaft sensor although the vehicle is moving according to other speeds. Toyota's bulletin for the U760 six-speed lists P0793 with P0717 and P0791 and replaces the countershaft sensor with a revised part. Ford reports the same fault under P0791 (below 250 rpm for 5 s). Note that a 2007 Allison table's 'P0793' for shift solenoid 1 low is a typo for P0973. Limp mode and check engine light follow.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Check engine light
• Limp mode
• Harsh shifts
• Accompanying codes P0717/P0791

Common causes

• High Sensor faulty (internal open circuit)
• Medium Wire open or connector loose
• Low Reluctor wheel or air gap
• Low Transmission module

Likelihood is a general estimate across vehicles; your make and model may differ.