Faulty intermediate shaft speed sensor C; Damaged or corroded wiring harness or connector at the sensor; Short to ground in the sensor signal circuit; Open circuit in the sensor power or ground circuit; Contaminated or degraded sensor mounting surface or reluctor wheel; PCM internal fault or software issue (rare)

DTC codes / P07xx · Transmission / P07C9

P07C9Intermediate Shaft Speed Sensor C Circuit Low

Q: What does code P07C9 mean?

Intermediate Shaft Speed Sensor C Circuit Low. P07C9 indicates that the powertrain control module (PCM) has detected an abnormally low voltage signal on the intermediate shaft speed sensor C circuit, which is used to monitor the rotational speed of an intermediate shaft in the transmission or transfer case. The PCM compares this signal to other speed sensors and sets the code when the voltage falls below the expected threshold for a calibrated time, indicating a short to ground, an open circuit, or a faulty sensor.

P07C9 indicates that the powertrain control module (PCM) has detected an abnormally low voltage signal on the intermediate shaft speed sensor C circuit, which is used to monitor the rotational speed of an intermediate shaft in the transmission or transfer case. The PCM compares this signal to other speed sensors and sets the code when the voltage falls below the expected threshold for a calibrated time, indicating a short to ground, an open circuit, or a faulty sensor.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaTransmission

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Harsh or delayed transmission shifts due to incorrect speed data
Transmission may enter limp mode or fail to shift into certain gears
Speedometer or tachometer readings may become erratic or inaccurate
Reduced fuel economy or abnormal engine RPM fluctuations
In some cases, the vehicle may stall or hesitate during acceleration

Common causes, most likely first

Faulty intermediate shaft speed sensor C
Damaged or corroded wiring harness or connector at the sensor
Short to ground in the sensor signal circuit
Open circuit in the sensor power or ground circuit
Contaminated or degraded sensor mounting surface or reluctor wheel
PCM internal fault or software issue (rare)

How to diagnose and fix it

Inspect the sensor and its connector for physical damage, corrosion, or loose pins, and clean or repair as needed
Check the sensor signal circuit for a short to ground using a digital multimeter and wiring diagram
Verify sensor resistance and compare to manufacturer specifications; replace if out of range
Test the sensor power and ground circuits for continuity and voltage drops
Inspect the reluctor wheel or tone ring for damage or debris and clean or replace if necessary
Repair any damaged wiring or connectors, then clear the code and test-drive the vehicle
If all circuits and components test good, reprogram or replace the PCM as a last resort

Speed Sensor C Circuit Low Diagnosis Traps

A low voltage code on a speed sensor circuit is frequently caused by a chafed wire shorting to ground rather than a failed sensor, so always perform a thorough visual and continuity check before replacing parts.
The intermediate shaft speed sensor C may share a ground or reference voltage with other sensors, and a fault in that shared circuit can set multiple speed sensor codes simultaneously.
Debris or metal shavings on the sensor tip or reluctor wheel can disrupt the magnetic signal and mimic a low voltage condition, especially after transmission work or fluid contamination.
In some transmissions, the intermediate shaft speed sensor is used for shift strategy and torque converter lockup, so a low signal may cause drivability issues that seem unrelated to speed sensing.
After repairing the circuit, the PCM may require a relearn or adaptation reset to restore normal shift quality, and simply clearing the code may not be enough.

Can I keep driving with P07C9?

You can usually drive the vehicle with this code, but expect degraded shift quality and possible limp mode; avoid aggressive acceleration or towing, and have the fault diagnosed promptly to prevent transmission damage.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.