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DTC codes / P07xx · Transmission / P07C3

P07C3Input/Turbine Shaft Speed Sensor C Circuit Low

P07C3 indicates that the transmission control module has detected an abnormally low voltage or signal on the 'C' input/turbine shaft speed sensor circuit, which measures the rotational speed of the transmission input shaft. The computer sets this code when the signal from that sensor falls below the expected range for the current operating conditions, often due to a wiring fault, poor connection, or sensor failure.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaTransmission

Symptoms you may notice

  • Illumination of the check engine light or transmission warning light
  • Harsh or delayed transmission shifts
  • Transmission may enter limp mode and stay in a single gear
  • Erratic or missing speedometer readings if the sensor shares data with the instrument cluster
  • Often no symptoms besides the warning light, especially if the fault is intermittent

Common causes, most likely first

  1. Damaged or corroded wiring or connector at the input/turbine shaft speed sensor
  2. Failed input/turbine shaft speed sensor
  3. Open or short to ground in the sensor signal circuit
  4. Poor electrical connection at the transmission control module
  5. Debris or metallic particles on the sensor tip interfering with the signal
  6. Internal transmission mechanical issue affecting the reluctor wheel or shaft

How to diagnose and fix it

  1. Inspect the sensor and its connector for physical damage, corrosion, or loose pins
  2. Check the sensor resistance and compare to the manufacturer's specification
  3. Verify the signal circuit for continuity and shorts to ground or power using a multimeter
  4. Inspect the reluctor wheel or tone ring for damage or debris if accessible
  5. Clear the code and test-drive to see if it returns; if it does, perform a wiggle test on the harness
  6. Replace the sensor if faulty and recheck the circuit
  7. If the circuit and sensor are good, diagnose the transmission control module or internal transmission components

Common misdiagnosis traps for P07C3

  • A low signal code often results from a poor connection or chafed wire rather than a failed sensor, so always inspect the harness before replacing parts.
  • Metallic debris from transmission wear can accumulate on the magnetic sensor tip and cause a low signal without any electrical fault.
  • This code can be set by a faulty transmission control module or a software issue, so check for technical service bulletins before condemning the module.
  • In some vehicles, the input shaft speed sensor shares a ground with other sensors, and a bad ground can cause multiple codes including P07C3.
  • A failing sensor may still produce a signal at low speeds but drop out at higher speeds, so a static resistance check may not reveal the fault.

Can I keep driving with P07C3?

If the transmission is shifting poorly or has entered limp mode, avoid driving at high speeds or under heavy load and seek repair promptly to prevent further damage. If the only symptom is the warning light and the vehicle drives normally, you can drive cautiously to a workshop, but have it checked soon.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

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

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