P07C8: Intermediate Shaft Speed Sensor B Circuit High

What does P07C8 mean?

These low/high codes are a purely electrical check of the sensor's signal voltage at the module and run even with the vehicle at rest – unlike the circuit, range, no-signal and intermittent codes, which evaluate speed while driving. Low means a short to ground, high a short to supply or, depending on the circuit, an open. Intermediate shaft sensor B is a further sensor on a countershaft or planetary element. No manufacturer document available to us uses this code; GM reports further 10-speed intermediate sensors under its own codes. The expected logic follows the other sensors (above about 4.75 V); the speed-based codes for sensor B are P2745–P2748.

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

Symptoms

• Check engine light (GM after one trip)
• Limp mode, harsh shifts, no converter lock-up
• Adaption frozen

Common causes

• High Signal wire shorted to supply
• Medium Open circuit or broken wire inside the sensor
• Medium Corroded connector
• Low Module input faulty

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