P0519 - Idle Air Control System Performance
System
Powertrain (Engine & Gearbox)
Technical Description
The control module has detected a fault in the Idle Air Control System Performance (P0519).
Multimeter Test Points & Nominal Values
| Test Point / Component | Measurement | Nominal Target Range | Test Condition |
|---|---|---|---|
| Idle Air Control System Performance – Coil Resistance | Resistance (Ω) | 20 - 120 Ω (relay) / 8 - 40 Ω (solenoid) | Device disconnected at 20°C |
| Idle Air Control System Performance – Supply Voltage | Voltage (V) | 11.8 - 14.4 V | Ignition ON, high side of load |
| Idle Air Control System Performance – Control (Low Side) Rest / Active | Voltage (V) | Rest ≈ battery voltage / Active < 1.0 V | Module commanding device ON/OFF |
Device disconnected at 20°C
Ignition ON, high side of load
Module commanding device ON/OFF
Oscilloscope Waveform Analysis
5 ms/div, 50 V/divPossible Causes
Idle Air Control System Performance is electrically operational but performing outside calibrated tolerance
Chafed or pinched wiring harness along the signal path to Idle Air Control System Performance
Internal mechanical wear or carbon deposits inside Idle Air Control System Performance
Defective internal output driver or reference circuit in the control module for Idle Air Control System Performance
Symptoms
4
Recommended Solution
Verify underlying mechanical operation and rule out blockage, vacuum leaks, or mechanical binding.
Verify loaded supply voltage and harness terminal pins at Idle Air Control System Performance.
Check circuit continuity and ground-side voltage drop (< 0.05 V) for Idle Air Control System Performance.
Command device via scan-tool bidirectional control to verify mechanical operation and flyback spike.
Mechanic's Tip
When an inductive relay/solenoid turns off, an inductive flyback spike (60 - 300 V) MUST appear on the scope. Absence of the spike indicates an open coil winding or an open module driver.