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DTC codes / P07xx · Transmission / P0708

P0708Transmission Range Sensor Circuit High

P0708 means the transmission range sensor, also called the park/neutral position switch, is sending a voltage signal to the transmission control module that is higher than the expected range for the selected gear. The computer compares the sensor's output against the range it expects for the gear lever position and flags the circuit as high when the voltage stays above the calibrated threshold.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaTransmission

Symptoms you may notice

  • The check engine light or transmission warning light is illuminated on the dashboard.
  • The engine may crank but not start because the computer cannot confirm the selector is in Park or Neutral.
  • The gear indicator on the instrument cluster may be blank, flashing, or show the wrong position.
  • Shifting may feel harsh or delayed, or the transmission may stay in a single gear as a failsafe.
  • The reverse lights may fail to come on, or may stay on continuously.
  • Often no symptoms besides the warning light, especially if the fault is intermittent.

Common causes, most likely first

  1. A faulty transmission range sensor with an internally open or shorted circuit that drives the signal voltage high.
  2. Corroded, bent, or pushed-back pins in the sensor connector or the transmission control module connector.
  3. A chafed or broken signal wire shorted to a power source along the harness, often near the transmission or firewall.
  4. A poor ground connection at the sensor or the transmission case, which raises the reference voltage seen by the module.
  5. Water or oil intrusion into the sensor connector causing resistance and voltage drift.
  6. A misadjusted sensor or selector cable that places the sensor outside its expected voltage window for the indicated gear.
  7. A rare internal fault in the transmission control module itself, which is the least likely cause and should be confirmed last.

How to diagnose and fix it

  1. Scan all modules and record freeze-frame data for P0708, then clear the code and test-drive to confirm whether it returns immediately or only under specific conditions.
  2. Inspect the transmission range sensor connector and harness for corrosion, chafing, or pushed pins, and repair any damaged terminals before replacing parts.
  3. Backprobe the sensor signal wire at the module and compare the measured voltage against the manufacturer's range chart for each gear selector position.
  4. Check the sensor ground circuit for excessive voltage drop under load, and clean or repair the ground point if resistance is high.
  5. Verify sensor alignment and selector cable adjustment, then recheck the voltage sweep through all gear positions.
  6. Replace the transmission range sensor if the voltage signal is out of range at the sensor itself, then clear codes and confirm the fix with a road test.
  7. If the signal is correct at the sensor but high at the module, trace the harness for a short to voltage and repair the affected section.

What the range sensor voltage really tells you

  • A high signal voltage often comes from a bad ground rather than a failed sensor, so check ground voltage drop before condemning the part.
  • The range sensor shares its signal circuit with the starter enable logic on many vehicles, which is why a no-crank complaint can accompany P0708.
  • Aftermarket sensors and incorrect installation angle are a common cause of repeat P0708 codes, so verify the replacement matches the original calibration.
  • A shorted signal wire can be intermittent and only set the code when the engine moves under load, so wiggle-test the harness while watching live data.
  • P0708 does not always mean the sensor is bad; a misadjusted selector cable can push the sensor outside its expected voltage window and set the same code.

Can I keep driving with P0708?

The vehicle may enter a limp or failsafe mode and refuse to start in Park or Neutral, so avoid long trips and do not rely on the reverse lights. If the transmission is stuck in one gear or the engine will not crank, stop driving and have the circuit diagnosed before further use.

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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