Gate Select Position Circuit Intermittent
The P0908 code indicates that the Powertrain Control Module (PCM) or Transmission Control Module (TCM) has detected an erratic or intermittent signal from the transmission gate select position circuit. This sensor tells the computer which gear track (gate) the shifter is currently aligned with, and an intermittent signal prevents proper gear engagement.
An intermittent gate select position signal can cause the transmission to get stuck in gear, fail to shift, or enter limp mode. This can leave the vehicle stranded or make it unsafe to drive in traffic, requiring immediate diagnosis.
Common symptoms
- Illuminated Check Engine Light
- Transmission refuses to shift gears
- Vehicle stuck in a single gear or limp mode
- Harsh or erratic shifting behavior
- Gear indicator on the dashboard flashes or displays incorrectly
Likely causes
- Loose, corroded, or damaged wiring and connectors in the gate select position circuit
- Faulty gate select position sensor
- Misadjusted gate select position sensor or shift linkage
- Mechanical wear or damage inside the transmission shift mechanism
- Faulty Transmission Control Module (TCM)
What to check before replacing parts
Inspect the wiring harness and connectors
Look for: Look for loose pins, corrosion, water intrusion, or chafed wires leading to the gate select position sensor that could cause an intermittent connection.
Monitor sensor data with an advanced scan tool
Look for: Observe the gate select position PID while moving the shifter or wiggling the harness; look for erratic voltage drops, spikes, or signal dropouts.
Test the sensor's power and ground circuits
Look for: Verify a steady 5-volt reference and a solid ground at the sensor connector using a digital multimeter. Fluctuations indicate a wiring issue.
Check the sensor resistance or voltage sweep
Look for: Sweep the shifter through its range and look for smooth, linear resistance or voltage changes without open circuits or dead spots.
Inspect the mechanical shift linkage and gate mechanism
Look for: Look for excessive play, binding, or wear in the physical linkage that could cause the sensor to read erratically or move out of alignment.
This page explains the generic P0908 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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