The P0708 code indicates a Transmission Range Sensor (TRS) circuit malfunction where the input voltage signal is abnormally high. This sensor—sometimes called the **neutral safety switch**—tells the ECM/TCM which gear the transmission is in (Park, Reverse, Neutral, or Drive). When the voltage exceeds expected limits, the system cannot correctly identify the gear position, triggering the Check Engine or Transmission light.

Commonly found in Honda Accord, Ford Fusion, Toyota Camry, and Nissan Altima, this fault can cause hard shifting, limp mode, or the vehicle not starting at all. Using the iCarsoft CR PRO S, you can view real-time TRS voltage data, confirm wiring integrity, and perform system resets after repair.

🔍 What Does the P0708 Code Mean?

The ECM or TCM receives multiple voltage signals from the TRS to determine the selected gear. If two or more signals show a high reading simultaneously, or one signal is stuck “high,” the module logs P0708 Transmission Range Sensor Circuit High Input. This typically indicates a short to voltage, damaged connector, or misaligned TRS.

⚠️ Common Symptoms of P0708

• Check Engine or Transmission Warning Light
• Vehicle stuck in limp mode
• Hard or delayed shifting between gears
• Engine won’t start (especially if gear signal misread)
• Transmission indicator on dash flickers or displays wrong gear

🔧 Common Causes of P0708

• Faulty Transmission Range Sensor (TRS) or neutral safety switch
• Corroded or loose TRS electrical connector
• Short to voltage in TRS wiring harness
• Incorrectly installed or misaligned TRS after service
• Internal TCM fault (rare)

🧰 How to Diagnose P0708 with iCarsoft CR PRO S

The iCarsoft CR PRO S offers live transmission data and bi-directional controls to pinpoint TRS faults quickly:

1. Connect CR PRO S to the OBD-II port and turn ignition ON (engine off).
2. Select your vehicle brand → Transmission Control Module.
3. Read DTCs to confirm P0708.
4. Go to Live Data → monitor “Gear Position Sensor Voltage.”
5. Move the gear selector through all positions (P, R, N, D).
6. Voltage should change smoothly; if one signal stays high (~5V), inspect wiring or TRS alignment.
7. Check for corrosion or fluid contamination inside the TRS connector.
8. After repair, clear DTCs and verify gear position data updates correctly.

🧠 Real-World Case: Honda Accord with P0708

A 2017 Honda Accord displayed “Check Transmission” and the P0708 code. The iCarsoft CR PRO S live data showed all gear voltage signals active simultaneously. Inspection revealed moisture intrusion inside the TRS connector. After cleaning and resealing the connector, voltage normalized, and the fault cleared. The car’s shifting returned to normal immediately.

💡 Pro Tips

• Always check battery voltage first—low system voltage can skew TRS readings.
• If you replaced the sensor, ensure proper alignment using OEM procedure (see manufacturer’s service manual).
• Use dielectric grease to protect TRS connectors from water intrusion.
• After clearing P0708, perform a Gear Learning/Adaptation Reset via CR PRO S if available.

❓ FAQ: P0708 Code

• Can I drive with the P0708 code?
  Driving with P0708 can trigger limp mode and unpredictable shifting. It’s best to diagnose it promptly.
• How do I test the transmission range sensor?
  Use iCarsoft CR PRO S to view TRS voltages while shifting gears. If readings stay constant, replace or realign the sensor.
• Does P0708 mean my transmission is bad?
  Not necessarily. Most cases are caused by wiring or sensor faults, not internal transmission failure.
• Can the P0708 code cause no-start?
  Yes. The ECM may not allow starting if it cannot confirm the vehicle is in Park or Neutral.
• Should I replace the TRS or the entire shifter assembly?
  Replace the TRS only if possible. Some models integrate it into the shifter—refer to your vehicle’s repair guide.

📘 Final Thoughts

The P0708 Transmission Range Sensor Circuit High Input is a signal voltage fault that can disable normal shifting and engine start. With the iCarsoft CR PRO S, you can easily view live TRS voltage values, identify wiring shorts, and clear codes after confirming proper gear signal operation. Diagnosing early prevents further wear on your transmission and ensures safe, reliable driving.