P1637 — Throttle Valve Position Control Control Deviation

Causes

• Faulty electronic throttle body (throttle actuator/motor or position sensor)
• Wiring issues: damaged harness, corroded or loose connectors, poor ground
• Throttle plate binding or mechanical obstruction (carbon buildup, foreign debris)
• Incorrect or lost throttle adaptation/learn values (battery disconnect or failed adaptation)
• Faulty accelerator pedal position sensor / sensor disagreement
• DME/software fault or corrupted calibration

Symptoms

• Malfunction Indicator Lamp (MIL) / Check Engine Light illuminated
• Reduced engine power / limp-home mode
• Poor idle, surging, stumbling or hesitation on acceleration
• Lack of throttle response or unexpected throttle behavior
• Intermittent stalling or inability to maintain idle
• Possible poor fuel economy or elevated emissions

What to check

• Read and record all stored DTCs and freeze frame data with a capable BMW scan tool
• Check battery voltage and condition; ensure stable supply (12.4–12.9 V at key on, engine off)
• Inspect throttle body connector and wiring for corrosion, damage, or loose pins
• Verify accelerator pedal position sensors and compare both sensor channels for plausibility
• Use live data to compare commanded throttle angle vs actual throttle plate angle and note the delta
• Check for carbon buildup or mechanical obstruction at the throttle plate

Signal parameters

• Desired/Commanded throttle angle (degrees or % open) — should follow pedal input
• Actual throttle plate angle/position (degrees or % open) — should track commanded value
• Delta between commanded and actual throttle angle — fault typically set when delta exceeds manufacturer threshold (commonly > ~10° or ~10–15%)
• Accelerator pedal sensor 1 / sensor 2 voltage or % — both should track and not show implausible difference
• Reference voltage to throttle sensors ~5 V (check for stable supply)
• Battery supply voltage to actuator (approx. 12 V) while cranking/running

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