P0510 – Closed Throttle Position Switch

P0510 means the ECU has detected a malfunction in the Closed Throttle Position (CTP) switch — the component responsible for telling the engine computer when the throttle plate is fully closed. When this switch fails or sends incorrect signals, the ECU cannot properly control idle speed, fuel delivery, or deceleration logic. This often leads to rough idle, poor throttle response, or stalling when the throttle snaps shut. In this guide, you’ll learn exactly what P0510 means, what causes it, how to diagnose it correctly, and the repairs that typically solve the issue.

What Does P0510 Mean?

P0510 sets when the ECU does not receive the expected “closed throttle” signal from the throttle position sensor (TPS) assembly or dedicated Closed Throttle Position (CTP) switch. On older vehicles, this is a separate switch mounted on or inside the throttle body. On modern drive-by-wire systems, the function is built into the electronic throttle body and monitored through throttle plate angle.

If the ECU thinks the throttle is not closed—even when the plate physically is—it cannot activate idle control strategies, fuel cut-off on deceleration, or proper idle air bypass functions. This results in unstable idle, hanging RPM, or difficulty starting.

Quick Reference

  • OBD-II Family: P-Code (Powertrain)
  • Scope: Generic
  • System: Throttle Position / Idle Detection
  • Difficulty Level: Moderate
  • Estimated Repair Cost: €40–€200
  • Last Updated: 2025-11-24

Real-World Example / Field Notes

Older Hyundai, Mitsubishi, and Mazda models commonly trigger P0510 when the internal throttle body switch wears out. One Mitsubishi Lancer case showed high idle and RPM that would “hang” during gear shifts. The CTP switch inside the TPS assembly wasn’t sending a closed-throttle signal, causing the ECU to maintain fuel even with the plate shut. Replacing the TPS sensor assembly fixed the issue immediately. On drive-by-wire Toyotas, P0510 often appears after throttle body cleaning if the plate doesn’t fully reseat or the idle relearn wasn’t performed.

Symptoms of P0510

  • High or hanging idle: RPM stays elevated when the throttle is released.
  • Poor throttle response: Delay or sluggish reaction when accelerating.
  • Stalling: Especially when coming to a stop or during sudden deceleration.
  • Rough idle: ECU can’t properly enter idle mode.
  • Hard starting: Incorrect throttle position data disrupts fueling.
  • Check Engine Light: Stored with P0510 and sometimes other TPS-related codes.

Common Causes of P0510

Most Common Causes

  • Faulty Closed Throttle Position (CTP) switch inside the TPS assembly.
  • Incorrect throttle plate position due to carbon buildup.
  • Loose, damaged, or corroded TPS/CTP connector pins.
  • Faulty electronic throttle body position sensor (drive-by-wire vehicles).
  • Wiring damage between TPS and ECU.

Less Common Causes

  • Incorrect throttle body installation or misalignment.
  • Faulty idle learn values after battery disconnection.
  • ECU driver malfunction (rare).
  • Physical throttle plate not fully closing due to debris.
  • Aftermarket TPS with incorrect internal switching logic.

Diagnosis: Step-by-Step Guide

Your goal is to determine whether the throttle is not being sensed as “closed” due to electrical issues, mechanical restriction, or sensor failure.

Tools You’ll Need: OBD-II scanner, multimeter, wiring diagram, throttle cleaner, feeler gauge (optional), and a scan tool capable of live TPS and throttle angle data.

  1. Check live TPS data. At closed throttle, TPS should read around 0–1%. Higher values indicate a bad sensor or stuck throttle plate.
  2. Inspect the throttle body for dirt or carbon. Clean the throttle plate and bore if airflow is restricted or the plate doesn’t fully close.
  3. Inspect TPS/CTP connector. Look for corrosion, loose pins, or moisture contamination.
  4. Check wiring continuity. Verify signal and ground wires between the throttle body/TPS and the ECU.
  5. Test the TPS/CTP switch resistance. On older vehicles, confirm the switch closes when the throttle is at rest.
  6. Verify throttle plate return. Ensure the plate isn’t sticking due to mechanical wear or carbon buildup.
  7. Perform throttle relearn. Necessary after throttle cleaning or battery disconnect on many vehicles.
  8. Inspect electronic throttle body (ETC) function. Look for erratic throttle angle or inconsistent idle control.
  9. Evaluate battery voltage. Low voltage can cause throttle electronics to malfunction.
  10. Check for aftermarket or misadjusted throttle components. Misalignment can prevent the throttle from reaching “closed” position.

Pro Tip: If TPS data reads consistently above 1–2% at rest, the ECU will not enter idle mode — even if the plate is physically closed. In these cases, TPS or throttle body replacement is often required.

Possible Fixes & Repair Costs

  • Replace TPS/CTP sensor assembly: Most common fix (€40–€120).
  • Clean throttle body: Ensures correct plate closure (€0–€40).
  • Perform throttle relearn: Required after cleaning (€0–€60).
  • Repair wiring or connectors: €10–€60 depending on damage.
  • Replace electronic throttle body: If the internal position sensor fails (€100–€200).
  • Fix mechanical throttle plate sticking: Cleaning or adjustment (€0–€40).

Always confirm the throttle plate is fully closing and the TPS is reporting accurate zero-angle data before replacing components.

Can I Still Drive With P0510?

In many cases, yes — but symptoms like high idle, stalling, or hesitation can make driving unpredictable. If RPM hangs or the engine surges when shifting, avoid driving until repairs are made. A malfunctioning CTP switch can affect throttle control, which is critical for safe operation.

Related Codes

  • P0574 – Cruise Control System Vehicle Speed Too High
  • P0573 – Brake Switch “A” Circuit High
  • P0572 – Brake Switch “A” Circuit Low
  • P0571 – Brake Switch “A” Circuit
  • P0570 – Cruise Control Accelerate Signal
  • P0569 – Cruise Control Coast Signal
  • P0568 – Cruise Control Set Signal
  • P0567 – Cruise Control Resume Signal
  • P0566 – Cruise Control Off Signal
  • P0565 – Cruise Control On Signal

Key Takeaways

  • P0510 indicates a failure in the closed-throttle detection system.
  • Most causes involve TPS failure, wiring issues, or a dirty throttle body.
  • Driving may be unsafe if high idle or stalling occurs.
  • Live TPS data and throttle relearn procedures are essential for diagnosis.

FAQ

What causes P0510 most often?

Typically a worn TPS/CTP switch or a throttle body that doesn’t fully close due to carbon buildup. Wiring issues are also common.

Can cleaning the throttle body fix P0510?

Yes — if carbon buildup prevents the throttle from closing completely, cleaning is often enough to restore proper CTP switching.

Is the TPS the same as the CTP switch?

On many older vehicles the CTP switch is integrated into the TPS assembly. On others, it may be separate. Modern vehicles use electronic throttle logic instead of a physical switch.

Can I drive with P0510?

You can, but high idle or stalling can make driving unsafe. Address the issue soon to avoid unpredictable engine behavior.

How do I diagnose P0510?

Check TPS live data, test sensor resistance, inspect wiring, ensure the throttle plate closes fully, and perform a throttle relearn if needed.