My engine is idling too high

How long since a tune-up? Check for applicable mil codes, you can check those codes, yourself. You turn the key just till the dash lites come on, no crank, Cycle the key on--off, on--off, on, then the mil starts flashing, you count the flashes to get the codes. Your looking for two digit codes.

Possible vacuum leak?

Hi,

Idle speed on this vehicle is controlled by the idle air control motor. It is mounted on the throttle body. Make sure the wiring wasn't damaged or the plug disconnected.

If the wiring all looks good, here is a link that explains how to service it:

https://www.2carpros.com/articles/idle-air-control-valve-service

Here is a link that explains in general how one is replaced:

https://www.2carpros.com/articles/how-to-replace-an-idle-speed-control-motor-iac

If everything looks good, here is a link that explains how to replace it. It is specific to your vehicle. The attached pics correlate with the directions.

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2002 Dodge Neon L4-2.0L VIN C
Procedures
Vehicle Powertrain Management Fuel Delivery and Air Induction Idle Speed/Throttle Actuator - Electronic Service and Repair Procedures
PROCEDURES
REMOVAL
When servicing throttle body components, always reassemble components with new O-rings and seals where applicable. Never use lubricants on O-rings or seals, damage may result. If assembly of component is difficult, use water to aid assembly Use care when removing hoses to prevent damage to hose or hose nipple.
1. Disconnect negative cable from battery.
2. Remove electrical connector from idle air control motor.

Fig.17 Servicing Idle Air Control Motor

pic 1

3. Remove idle air control motor mounting screws.
4. Remove motor from throttle body. Ensure the O-ring is removed with the motor.

INSTALLATION
When servicing throttle body components, always reassemble components with new O-rings and seals where applicable. Never use lubricants on O-rings or seals, damage may result. If assembly of component is difficult, use water to aid assembly Use care when removing hoses to prevent damage to hose or hose nipple.
1. The new idle air control motor has a new O-ring installed on it. If pintle measures more than 1 inch (25 mm) it must be retracted. Use the DRB III Idle Air Control Motor Open/Close Test to retract the pintle (battery must be connected.)
2. Carefully place idle air control motor into throttle body.
3. Install mounting screws. Tighten screws to 4.5 Nm (40 in. lbs.) torque.
4. Connect electrical connector to idle air control motor.
5. Connect negative cable to battery.

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I hope this helps. Let me know if you have other questions.

Take care and God Bless,

Joe