The idling speed is higher than normal regardless of the engine coolant temperature.
Perform the Diagnostic system check - engine controls.
Inspect whether the harness connector is properly connected.
Compare the Engine Speed parameter on the scan tool with the value of the tachometer in the instrument panel cluster.
Inspect the battery voltage. If the battery voltage is less than 11 V, the ECM sets the idle speed higher than the normal value by 50 rpm.
Inspect the operation of the A/C.
Inspect the fuel type and quality.
Inspect the engine oil level.
Check the scan tool data list.
Check for related Service Bulletins.
Compare the Engine Coolant Temperature (ECT), Intake Air Temperature (IAT), and Fuel Temperature parameters while the engine is cold. If the difference between the temperature values is 5°C {9°F} or more when the engine is cold, inspect for high resistance in each circuit and for a sensor malfunction.
{When the ignition switch is turned ON, the MAF sensor is heated, and as a result, the IAT shows a higher value than the normal intake air temperature.}
Observe the Fuel Rail Pressure (FRP) Sensor parameter on the scan tool. It is normal if the Fuel Rail Pressure (FRP) Sensor parameter shows approximately 20 MPa or more when the ignition switch is turned ON without starting the engine after the engine operation is stopped. If not, inspect for high resistance in each circuit and for a sensor malfunction.
When idling the engine in neutral, observe the Fuel Rail Pressure (FRP) parameter. It is normal if the value is always in the range of 27 to 33 MPa {3,900 to 4,800 psi} after the engine is warmed up.
Observe the Accelerator Pedal Position (APP) parameter. It is normal if the Accelerator Pedal Position (APP) parameter changes linearly from 0 to 100% according to the accelerator pedal operation.
Remove and visually inspect the injector.
{The tip of the injector may be damaged.}