Vacuum leak from a cracked or disconnected intake hose, PCV hose, or intake manifold gasket; Dirty or failing mass air flow (MAF) sensor reporting less air than actually enters; Leaking intake manifold gasket or throttle body gasket allowing unmetered air; Sticking or contaminated idle air control (IAC) valve or electronic throttle body carbon buildup; Weak fuel pump or restricted fuel filter causing low fuel pressure at idle; Leaking fuel injector O-rings or a faulty injector affecting idle mixture; Crankcase ventilation system fault, such as a failed PCV valve or breather hose, altering idle airflow

DTC codes / Volkswagen codes / P1507

P1507 · VolkswagenIdle System Learned Value Lower Limit Attained

Q: What does code P1507 mean?

Idle System Learned Value Lower Limit Attained. P1507 on a Volkswagen means the engine control module (ECM) has learned an idle trim value that has hit its lowest allowed limit, so the engine is running leaner at idle than the computer can compensate for. The ECM stores this code when the long-term idle adaptation value stays pinned at the bottom of its range during closed-loop idle operation.

P1507 on a Volkswagen means the engine control module (ECM) has learned an idle trim value that has hit its lowest allowed limit, so the engine is running leaner at idle than the computer can compensate for. The ECM stores this code when the long-term idle adaptation value stays pinned at the bottom of its range during closed-loop idle operation.

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 lean condition is mild
Rough or unstable idle, sometimes with a slight shake at stoplights
Idle speed that hangs high or dips low when coming to a stop
Occasional hesitation or stumble when accelerating from idle
Poor fuel economy if the lean condition persists
A faint fuel or vacuum smell in the engine bay from a small leak

Common causes, most likely first

Vacuum leak from a cracked or disconnected intake hose, PCV hose, or intake manifold gasket
Dirty or failing mass air flow (MAF) sensor reporting less air than actually enters
Leaking intake manifold gasket or throttle body gasket allowing unmetered air
Sticking or contaminated idle air control (IAC) valve or electronic throttle body carbon buildup
Weak fuel pump or restricted fuel filter causing low fuel pressure at idle
Leaking fuel injector O-rings or a faulty injector affecting idle mixture
Crankcase ventilation system fault, such as a failed PCV valve or breather hose, altering idle airflow

How to diagnose and fix it

Scan all modules and record freeze-frame data for P1507, then clear the code and verify it returns under idle conditions
Inspect the intake tract and vacuum hoses for cracks, loose clamps, and disconnected lines using a smoke machine or carb cleaner
Clean the throttle body and idle air control passages, then perform a throttle body adaptation reset with a scan tool
Check MAF sensor readings against expected values at idle and under load, and clean or replace the sensor if contaminated
Measure fuel pressure at idle and under load, and inspect the fuel filter and pump for restrictions
Perform a propane or smoke test around the intake manifold gasket and injector seals to find hidden leaks
After repairs, clear adaptations and drive the vehicle through a complete idle learn cycle, then confirm P1507 does not return

Idle learn limits and hidden vacuum leaks

A P1507 often sets without any driveability complaint because the ECM has already pushed the idle mixture as far lean as it can, masking the leak at normal speeds.
Technicians frequently replace the MAF sensor first, but a smoke test of the intake system finds the real cause in most cases and costs far less.
On many Volkswagen engines, a dirty throttle body alone can push the idle adaptation to its lower limit, so cleaning and re-adapting the throttle is a smart first repair.
The code can be triggered by a failing PCV valve or a cracked breather hose that only leaks at idle vacuum, so inspect the crankcase ventilation system carefully.
After any repair, the ECM must relearn idle; skipping the adaptation reset can make P1507 reappear even when the mechanical fault is fixed.

Can I keep driving with P1507?

You can usually drive the car short distances to a repair shop, but avoid prolonged idling and heavy loads because a lean idle mixture can raise combustion temperatures. If the check engine light starts flashing or the engine runs very rough, stop driving and have it towed.

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.