P1639 — BMW — Throttle Valve Position Control Throttle Stuck Permanently

Throttle Valve Position Control Throttle Stuck Permanently. Source catalogue definition; confirm applicability using vehicle service information.

Affected system: Powertrain

Symptoms

• Engine enters fail-safe or limp mode
• Noticeable loss of engine power
• Illumination of the check engine light
• Rough or erratic idle speed
• Unresponsive throttle pedal input

Possible causes

• Physical blockage in the throttle body assembly
• Internal failure of the throttle actuator motor
• Faulty throttle position sensor (TPS)
• Wiring harness shorts or open circuits to the throttle body
• Corroded or loose electrical connector pins
• Damaged internal throttle plate gears

What to check

• Inspect the throttle body for carbon deposits or physical obstructions preventing movement
• Test the electrical connector pins for signs of corrosion or terminal spread
• Measure the voltage and ground supply at the throttle body harness connector
• Perform a range-of-motion test using a diagnostic scanner to command the throttle plate
• Check the wiring harness integrity for continuity and short-to-ground conditions
• Verify proper operation of the throttle actuator motor via resistance testing