P0908: Gate Select Position Circuit Intermittent

What it means

The gate select position circuit A reports a circuit a intermittent fault. Selector gate position cannot be reliably measured.

At a glance

• Usually lights the check-engine light
• The engine or gearbox may go into limp mode

How it works

The gate select position sensor tells the TCM which shift gate the selector has reached. This code sets when circuit A's signal drops in and out or becomes erratic, so the TCM cannot rely on the reported gate position.

Common causes

Most likely first.

1. Connector not seated
2. Noisy ground reference
3. Connector with intermittent contact under vibration

Symptoms

• Check engine or transmission warning light on
• Harsh, delayed, or missing shifts
• Possible limp mode (locked in one gear)
• Slipping or shuddering during gear changes

How to diagnose it

1. Save freeze-frame data and watch live gate-position data to identify whether circuit A becomes erratic during a shift, vibration, or temperature change.
2. Inspect the sensor connector for incomplete seating, loose terminals, corrosion, moisture, and signs that a pin moves in the connector body.
3. Check the sensor ground and reference connections for looseness or instability, then compare readings with the manufacturer's specification.
4. Monitor circuit A while gently moving the harness and connector to find an intermittent break or contact, taking care not to short the circuit.
5. If the wiring and ground remain stable, test the sensor output through its operating range and replace the sensor if its signal drops out.

Common fixes

• Seat and secure the gate-position sensor connector.
• Clean corroded terminals and repair loose or damaged connector pins.
• Repair a damaged ground or reference connection.
• Repair or replace wiring that loses contact when moved.
• Replace the sensor if its output remains intermittent with sound wiring.

Can I keep driving?

Limit driving and avoid busy traffic if shifts are delayed, harsh, or unpredictable; stop if the transmission enters limp mode or loses drive. An intermittent position signal can trigger a sudden shift limitation and make the vehicle difficult to control.