Transmission Range Sensor Circuit Low
Diagnostic trouble code P0707 indicates that the powertrain control module (PCM) has detected an abnormally low voltage signal from the transmission range sensor circuit. This means the voltage has dropped below the manufacturer's specified operating threshold, preventing the computer from accurately determining the gear selector's position.
This code is considered high severity because the vehicle may fail to start if the computer cannot verify the transmission is in Park or Neutral. It can also cause erratic, unpredictable, and unsafe transmission shifting while driving.
Common symptoms
- Illuminated Check Engine Light
- Engine will not crank or start
- Incorrect or missing gear indicator display on the dashboard
- Harsh, delayed, or erratic transmission shifting
- Transmission defaults to a fail-safe or limp mode (stuck in one gear)
Likely causes
- Defective transmission range sensor (also known as a PRNDL switch or neutral safety switch)
- Short to ground in the transmission range sensor wiring circuit
- Corroded, damaged, or loose electrical connector at the sensor
- Misadjusted transmission range sensor or shift linkage/cable
- Internal transmission wiring harness failure (for internally mounted sensors)
- Faulty Powertrain Control Module (PCM) or Transmission Control Module (TCM) (rare)
What to check before replacing parts
Visually inspect the transmission range sensor, wiring harness, and connectors.
Look for: Look for frayed wires, melted insulation, severe corrosion, or loose pins that could cause a short to ground or poor connection.
Verify the adjustment of the shift cable and the transmission range sensor.
Look for: Ensure the mechanical linkage moves the sensor to the correct detents matching the gear selector position, as a misaligned sensor can output incorrect voltage.
Test the reference voltage and ground circuits at the sensor connector using a digital multimeter.
Look for: With the key on, engine off, verify the presence of the manufacturer-specified reference voltage (usually 5V) and a solid ground; a missing reference voltage indicates an upstream wiring or module issue.
Test the transmission range sensor's internal resistance or voltage output through all gear positions.
Look for: Compare the resistance or voltage readings in Park, Reverse, Neutral, and Drive against the manufacturer's service manual specifications to confirm if the sensor itself has failed internally.
Perform a continuity and short-to-ground test on the signal wire between the sensor and the PCM/TCM.
Look for: Disconnect both ends of the harness and check for continuity to ground on the signal wire; any continuity indicates a short to ground in the harness that must be repaired.
This page explains the generic P0707 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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