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DTC codes / P05xx · Vehicle speed, idle control and auxiliary inputs / P0510

P0510Closed Throttle Position Switch Malfunction

P0510 means the powertrain control module (PCM) has detected an unexpected signal from the closed throttle position switch, which is often integrated into the throttle position sensor (TPS) or accelerator pedal position (APP) sensor. The PCM expects a specific voltage or continuity state when the throttle is fully released, and it flags this code when the switch circuit stays open, stays closed, or behaves erratically.

SystemPowertrain
Code typeGeneric (all makes)
SeverityLow
Fix difficultyIntermediate
AreaVehicle speed, idle control and auxiliary inputs

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms.
  • A slightly rough or high idle, especially when coming to a stop.
  • Hesitation or a brief stumble when accelerating from a closed-throttle condition.
  • Inconsistent engine braking or deceleration feel.
  • In rare cases, the transmission may shift harshly or hold gears longer due to incorrect throttle input.
  • Poor fuel economy if the PCM defaults to a richer mixture based on a false closed-throttle signal.

Common causes, most likely first

  1. Worn or contaminated closed throttle position switch contacts inside the TPS or APP sensor assembly.
  2. A faulty throttle position sensor or accelerator pedal position sensor that includes the closed-throttle circuit.
  3. Damaged, chafed, or corroded wiring between the switch and the PCM.
  4. Loose or corroded electrical connector pins at the TPS, APP sensor, or PCM.
  5. A sticking or misadjusted throttle plate or accelerator pedal mechanism that prevents the switch from closing fully.
  6. A PCM software glitch or internal fault, though this is less common.
  7. Aftermarket or incorrectly installed throttle body or pedal assembly that does not match the factory closed-throttle specification.

How to diagnose and fix it

  1. Connect a scan tool and read live data to confirm the closed throttle position switch status changes from closed to open as the throttle is pressed.
  2. Inspect the TPS or APP sensor connector and wiring for corrosion, loose pins, or chafed insulation, and repair as needed.
  3. Check the throttle plate and accelerator pedal for binding or carbon buildup, and clean or adjust the mechanical linkage if applicable.
  4. Back-probe the switch signal wire at the PCM and verify voltage or continuity matches the factory service information for closed and open throttle.
  5. If the switch signal is correct at the PCM but the code persists, test the TPS or APP sensor with a multimeter for smooth resistance or voltage sweep.
  6. Replace the faulty TPS, APP sensor, or throttle body assembly only after confirming the switch circuit is defective.
  7. Clear the code and perform a throttle relearn or idle relearn procedure if required by the vehicle manufacturer.

Closed throttle switch checks most techs skip

  • A dirty throttle body can hold the throttle plate slightly open, preventing the closed throttle switch from making contact and setting P0510 even though the switch itself is fine.
  • On many drive-by-wire vehicles, the closed throttle position is inferred from the accelerator pedal sensor rather than a separate switch, so a faulty pedal assembly can trigger this code without any throttle body problem.
  • Technicians sometimes replace the TPS only to find the real issue is a worn ignition switch or poor ground that drops voltage to the sensor circuit under load.
  • P0510 can be set intermittently by a loose battery terminal or low system voltage, so always check battery and charging system health before condemning sensors.
  • A scan tool that shows closed throttle switch status may still lie if the PCM has adapted to a bad signal, so a physical voltage measurement at the sensor is the only reliable confirmation.

Can I keep driving with P0510?

You can generally continue driving with P0510 because the fault rarely causes a safety hazard, but avoid aggressive acceleration and monitor for idle or shifting issues. Have the circuit inspected soon to prevent drivability problems or increased emissions from worsening.

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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