LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Hyundai >> 1991 >> Sonata L4-2.4L >> Repair and Diagnosis >> Powertrain Management >> Relays and Modules - Powertrain Management >> Relays and Modules - Computers and Control Systems >> Engine Control Module >> Technical Service Bulletins >> All Technical Service Bulletins >> MIL ON DTC 15 Set >> Condition # 1
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Condition # 1


Symptom: Code 15 set in ECU, "Check Engine" light is on whenever the ignition is on.

Cause: Improper idle speed control servo assembly operation.





1. Motor position sensor may be faulty, which is likely to be caused by an incorrect adjustment of the fixed SAS.
2. Wires backed out of connectors.

Diagnosis: While watching the idle speed control solenoid, turn the ignition to "ON". The idle speed control solenoid should move out and then about 10 seconds later retract. Start the car and observe MPS reading on the MUT. The MPS should read 900-1300 mv at idle and increase as the accelerator pedal is depressed.

Correction: If the idle speed control solenoid does not move out or the MPS reading stays constant, replace the Idle Speed Control Servo Kit Ass'y.


You must then readjust the fixed SAS and curb idle according to the Shop Manual to prevent reoccurance of the condition!