Faulty closed throttle position switch (both sources). Open circuit or loose or dirty connection in the switch wiring (OBD-Codes.com; RepairPal lists a wiring issue). Throttle body idle set screw tampered with, so the linkage doesn't fully close the switch (OBD-Codes.com only). Faulty ECM or PCM (both sources).

Repair an open circuit or a loose or dirty connection in the switch wiring. Re-adjust the throttle idle set screw to the factory specification. Replace the closed throttle position switch, or the throttle position sensor where the switch is built in (RepairPal lists throttle position sensor replacement as the common repair). Repair or replace the ECM or PCM (rare, only after other causes are ruled out).

P0510🔧 Throttle / idle controlDrive with caution, fix soon

P0510: Closed Throttle Position Switch (Meaning, Causes, Fixes)

Q: What does P0510 mean?

P0510 means the engine computer is getting a wrong or missing signal from the closed throttle position switch, which tells it when the throttle is fully shut. Common causes are a faulty switch, an open or loose wiring connection, a tampered throttle idle set screw, or, rarely, the engine computer. On certain vehicles, the throttle body or throttle linkage has a switch that tells the powertrain control module (PCM) or engine control module (ECM) when the throttle is closed. When the throttle shuts, the switch is pressed closed. OBD-Codes.com says the computer uses this switch, together with the idle air control valve, to keep the engine at idle and to go into fuel cut mode while coasting. Some vehicles also have a wide open throttle (WOT) switch, and if either switch isn't engaged the computer may assume the throttle is partly open, which can affect the air/fuel ratio. RepairPal says P0510 sets when the PCM detects an incorrect signal from the closed throttle position switch. It is a generic OBD-II code that OBD-Codes.com says applies to 1996 and newer vehicles; on many cars the switch is part of the throttle position sensor (TPS). OBD-Codes.com notes that if P0120 (throttle position sensor circuit) is also stored, there may be an open ground circuit or a bad connection at the TPS.

Q: Can I keep driving with P0510?

Drive with caution, fix soon. RepairPal rates P0510 Moderate: it may not threaten the vehicle's safety or how it runs right away, but it should be diagnosed within a reasonable time. OBD-Codes.com says you will likely notice nothing besides the check engine light. Because the computer uses this switch to hold idle and to cut fuel while coasting, a bad signal can affect idle and the air/fuel mix, so don't ignore it.

Reviewed 2026-10-25 · Based on 2 cited source(s)

What P0510 means

On certain vehicles, the throttle body or throttle linkage has a switch that tells the powertrain control module (PCM) or engine control module (ECM) when the throttle is closed. When the throttle shuts, the switch is pressed closed. OBD-Codes.com says the computer uses this switch, together with the idle air control valve, to keep the engine at idle and to go into fuel cut mode while coasting. Some vehicles also have a wide open throttle (WOT) switch, and if either switch isn't engaged the computer may assume the throttle is partly open, which can affect the air/fuel ratio. RepairPal says P0510 sets when the PCM detects an incorrect signal from the closed throttle position switch. It is a generic OBD-II code that OBD-Codes.com says applies to 1996 and newer vehicles; on many cars the switch is part of the throttle position sensor (TPS). OBD-Codes.com notes that if P0120 (throttle position sensor circuit) is also stored, there may be an open ground circuit or a bad connection at the TPS.

Severity: can I keep driving?

Drive with caution, fix soon

RepairPal rates P0510 Moderate: it may not threaten the vehicle's safety or how it runs right away, but it should be diagnosed within a reasonable time. OBD-Codes.com says you will likely notice nothing besides the check engine light. Because the computer uses this switch to hold idle and to cut fuel while coasting, a bad signal can affect idle and the air/fuel mix, so don't ignore it.

Common symptoms

Check engine light on
Usually no other noticeable symptoms (OBD-Codes.com)

Likely causes

Roughly most to least common, based on the sources below. Your vehicle may differ.

Faulty closed throttle position switch (both sources)
Open circuit or loose or dirty connection in the switch wiring (OBD-Codes.com; RepairPal lists a wiring issue)
Throttle body idle set screw tampered with, so the linkage doesn't fully close the switch (OBD-Codes.com only)
Faulty ECM or PCM (both sources)

Diagnostic steps you can do

⚠ Before you start

Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.

Read all stored codes and freeze frame data and write them down. If P0120 or other throttle position codes are also stored, OBD-Codes.com says to suspect an open ground circuit or a bad connection at the throttle position sensor.
Inspect the connector at the throttle position sensor or closed throttle switch for looseness, dirt or corrosion.
Check that the throttle linkage fully closes and actually presses the switch. If someone has turned the idle set screw, it may need to be reset to the factory specification.
Clear the code and drive normally to see whether it returns.

Typical fixes

Repair an open circuit or a loose or dirty connection in the switch wiring
Re-adjust the throttle idle set screw to the factory specification
Replace the closed throttle position switch, or the throttle position sensor where the switch is built in (RepairPal lists throttle position sensor replacement as the common repair)
Repair or replace the ECM or PCM (rare, only after other causes are ruled out)

Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.

🛠 When to call a pro

You need to test the wiring and switch with a multimeter (OBD-Codes.com describes a continuity check of each wire between the switch and the computer using a wiring diagram, and checking the switch with the throttle closed)
The idle set screw needs adjusting and you don't have the factory procedure
The code keeps coming back after the wiring and switch check out

Where to buy

Plain search links. Always match parts to your exact year, make, model and engine.

OBD2 scanners on Amazon Parts at Advance Auto Parts catalog at RockAuto

FAQs

Is P0510 serious?

RepairPal rates it Moderate, meaning it isn't usually an immediate safety threat but should be diagnosed within a reasonable time. OBD-Codes.com says you will likely notice only the check engine light.

What is the most common cause of P0510?

Both sources list a failed closed throttle position switch, a wiring problem and, less often, the engine computer. OBD-Codes.com also lists a tampered throttle idle set screw that keeps the linkage from fully closing the switch.

Is the closed throttle position switch the same as the throttle position sensor?

On many vehicles the switch is part of the throttle position sensor, which is why RepairPal lists throttle position sensor replacement as the common repair. OBD-Codes.com describes testing at either the throttle position sensor or a separate closed throttle switch, depending on the vehicle.

Do the sources describe P0510 the same way?

Mostly. Both say the computer is getting a bad signal from the switch that reports a closed throttle. OBD-Codes.com adds the idle set screw as a cause and says there are usually no symptoms besides the check engine light; RepairPal doesn't list symptoms.

How much does it cost to fix P0510?

Neither source gives a repair cost. It depends on the cause, from cleaning a connector or adjusting the idle screw to a new switch or throttle position sensor, so get it diagnosed first.

Sources

Last reviewed 2026-10-25. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.