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DTC codes / P09xx · Transmission / P0908

P0908Gate Select Position Circuit Intermittent

P0908 means the transmission control module (TCM) has detected an intermittent fault in the electrical circuit for the gate select position sensor, which tells the computer which shift gate the gear lever is in. The TCM sees the signal from this sensor drop out or jump erratically for brief moments, rather than failing completely.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaTransmission

Symptoms you may notice

  • The gear position indicator on the dashboard may flicker or show the wrong range intermittently
  • The transmission may hesitate, slip, or engage the wrong gear for a split second
  • The check engine light or transmission warning light illuminates, sometimes only over bumps
  • The vehicle may refuse to start in Park or Neutral because the TCM cannot confirm the lever position
  • Often no symptoms besides the warning light, especially if the intermittent fault is brief

Common causes, most likely first

  1. A loose, corroded, or partially broken electrical connector at the gate select position sensor
  2. Chafed or internally broken wiring in the harness between the sensor and the TCM, often near a flex point
  3. A failing gate select position sensor with worn internal contacts that lose connection over bumps
  4. Water or oil intrusion into the sensor connector or the sensor housing
  5. Loose or damaged sensor mounting hardware allowing the sensor to move and lose its reference
  6. A TCM with an intermittent internal fault on the sensor input circuit, though this is less common

How to diagnose and fix it

  1. Scan all modules for stored and pending codes, and record freeze-frame data to see the conditions when P0908 set
  2. Inspect the gate select position sensor connector and harness for corrosion, loose pins, or chafing, and repair as needed
  3. Wiggle-test the sensor harness and connector while watching live gate position data on a scan tool to reproduce the intermittent fault
  4. Check the sensor's mounting and adjustment, and verify the sensor signal is stable through the full range of lever movement
  5. Measure the sensor circuit resistance and voltage drop with a multimeter, comparing against the manufacturer's specification
  6. Replace the gate select position sensor if the circuit tests good but the signal still drops out intermittently
  7. Clear the codes and perform a road test over varied surfaces to confirm the repair and that P0908 does not return

Intermittent faults hide in the harness

  • A gate select position sensor that tests perfectly on a stationary scan tool can still set P0908 because the fault only appears when the harness flexes over bumps or during engine movement.
  • Technicians often replace the sensor first, but a chafed wire or a backed-out terminal in the connector is just as common and far cheaper to fix.
  • P0908 does not mean the transmission is mechanically damaged; it is an electrical circuit fault, so internal transmission repairs are rarely the answer.
  • On some vehicles the gate select position signal is shared with the starter enable circuit, so an intermittent no-crank complaint can accompany this code.
  • Water intrusion from a clogged drain or a pressure-wash under the console can corrode the sensor connector and cause an intermittent signal that comes and goes with humidity.

Can I keep driving with P0908?

You can usually drive the vehicle to a shop, but avoid rough roads and hard acceleration that could make the fault worse, and do not ignore a transmission that occasionally engages the wrong gear. If the vehicle intermittently refuses to start or the transmission slips noticeably, stop driving and have it inspected promptly.

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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