Faulty idle speed control valve closing solenoid (open or shorted coil).; Damaged or corroded wiring harness between the DME and the idle control valve.; Loose or oxidized electrical connector at the idle speed control valve.; Internal DME driver circuit failure for the closing solenoid control.; Carbon buildup or mechanical binding inside the idle control valve causing abnormal current draw.; Aftermarket or incorrect idle control valve with mismatched solenoid resistance.

DTC codes / BMW codes / P1502

P1502 · BMWIdle Speed Control Valve Closing Solenoid Control Circuit Signal High Or Low

P1502 on a BMW indicates that the engine control module (DME) has detected an abnormal voltage signal on the control circuit for the closing solenoid inside the idle speed control valve. The DME expects a specific current draw or voltage pattern when commanding the valve to close, and the measured signal is either too high (open circuit) or too low (short to ground or excessive current).

SystemPowertrain

Code typeBMW 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 valve still moves freely.
Rough or erratic idle, sometimes fluctuating up and down (hunting idle).
Engine may stall when coming to a stop or when the throttle is released.
Inconsistent idle speed that may be too high or too low depending on the failure mode.
Occasional hesitation or stumble on acceleration from idle.
In severe cases, the engine may enter limp mode with reduced power.

Common causes, most likely first

Faulty idle speed control valve closing solenoid (open or shorted coil).
Damaged or corroded wiring harness between the DME and the idle control valve.
Loose or oxidized electrical connector at the idle speed control valve.
Internal DME driver circuit failure for the closing solenoid control.
Carbon buildup or mechanical binding inside the idle control valve causing abnormal current draw.
Aftermarket or incorrect idle control valve with mismatched solenoid resistance.

How to diagnose and fix it

Clear the fault code and perform a road test to see if P1502 returns; note any freeze-frame data.
Visually inspect the idle speed control valve connector and wiring for corrosion, chafing, or loose pins.
Measure the resistance of the closing solenoid coil at the valve connector and compare to BMW specifications.
Check for short-to-ground or short-to-power on the control circuit between the DME and the valve.
Test the DME output signal with an oscilloscope or bidirectional scan tool while commanding the valve closed.
Remove and clean the idle speed control valve to rule out carbon binding, then re-test.
If wiring and valve test good, suspect the DME and perform further diagnostics before replacement.

Before you replace the idle control valve

A common misdiagnosis is replacing the idle control valve when the real fault is a chafed wire in the harness near the intake manifold.
The DME driver for the closing solenoid can fail independently, so a new valve may not fix the code if the control circuit inside the DME is damaged.
Carbon buildup on the valve pintle can increase current draw and set P1502 without any visible driveability complaint.
On some BMW models, a weak battery or poor ground can cause voltage spikes that mimic a solenoid circuit fault.
Always check for related codes like P1501 or P1503, which may indicate a problem with the opening solenoid or the valve as a whole.

Can I keep driving with P1502?

You can usually drive the car with P1502 stored, but expect a rough or stalling idle that can be dangerous in traffic. Avoid prolonged idling and have the fault diagnosed promptly, especially if the engine stalls or enters limp mode.

Tools that help

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