Broken or chafed wire in the closed throttle position switch circuit, commonly at the throttle body connector; Corroded or loose electrical connector pins at the throttle body or engine control module; Failed closed throttle position switch inside the throttle body assembly; Throttle body mechanical wear or carbon buildup preventing the switch from closing; Faulty engine control module, though this is rare and should be the last suspect; Aftermarket or incorrectly adjusted throttle body replacement not matching the original switch logic

DTC codes / Volkswagen codes / P1505

P1505 · VolkswagenClosed Throttle Position Does Not Close Open Circuit

Q: What does code P1505 mean?

Closed Throttle Position Does Not Close Open Circuit. P1505 on Volkswagen vehicles means the engine control module has detected an open circuit in the closed throttle position switch circuit, so it cannot confirm the throttle is fully closed. The computer expects a specific voltage or continuity signal when the accelerator pedal is released, and that signal is missing or out of range.

P1505 on Volkswagen vehicles means the engine control module has detected an open circuit in the closed throttle position switch circuit, so it cannot confirm the throttle is fully closed. The computer expects a specific voltage or continuity signal when the accelerator pedal is released, and that signal is missing or out of range.

SystemPowertrain

Code typeVolkswagen specific

SeverityMedium

Fix difficultyIntermediate

AreaVehicle speed, idle control and auxiliary inputs

Symptoms you may notice

Often no symptoms besides the warning light, especially if the fault is intermittent
A slightly high or erratic idle because the engine computer cannot confirm closed throttle
Hesitation or a small stumble when lifting off the accelerator
Poor fuel economy if the computer defaults to a non-closed-throttle strategy
In some cases, a stored code with no drivability complaint at all

Common causes, most likely first

Broken or chafed wire in the closed throttle position switch circuit, commonly at the throttle body connector
Corroded or loose electrical connector pins at the throttle body or engine control module
Failed closed throttle position switch inside the throttle body assembly
Throttle body mechanical wear or carbon buildup preventing the switch from closing
Faulty engine control module, though this is rare and should be the last suspect
Aftermarket or incorrectly adjusted throttle body replacement not matching the original switch logic

How to diagnose and fix it

Scan all modules and record freeze-frame data to confirm when the open circuit was detected
Visually inspect the throttle body connector and wiring harness for chafing, corrosion, or loose pins
Measure resistance and continuity across the closed throttle position switch circuit with a multimeter while cycling the throttle
Check the switch signal at the engine control module connector to rule out a harness fault between the throttle body and the module
Clean the throttle body and perform a throttle body adaptation or basic setting with a scan tool
Replace the throttle body assembly if the switch is internal and proven faulty
Clear the code and verify the repair by monitoring closed throttle status in live data during a road test

Why the throttle body gets replaced too soon

A dirty throttle body often causes the closed throttle switch to stay off its contact, setting P1505 without any wiring fault at all, so cleaning and adaptation frequently fixes it.
Technicians who replace the throttle body before checking continuity at the module connector sometimes miss a chafed wire in the harness, and the code returns immediately after the new part is fitted.
On some Volkswagen models the closed throttle position signal is shared with the accelerator pedal switch circuit, so a pedal sensor fault can masquerade as a throttle body problem.
An aftermarket throttle body may not communicate the closed throttle signal in the same way as the original unit, causing a repeat P1505 even though the new part is not defective.
The code can be stored intermittently by a loose battery terminal or low voltage event that momentarily drops the switch signal, so check charging system health before condemning parts.

Can I keep driving with P1505?

You can usually drive the car, but avoid prolonged idling and be alert for a high or unstable idle that could affect braking and creeping in traffic. Have the fault diagnosed soon, because a confirmed closed throttle signal is needed for correct fuel cut and idle control.

Tools that help

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Guidance is general and written for Volkswagen vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.