Hyundai Repair: scanned code, intake manifold gasket, vacuum leaks

Question
QUESTION: I have a 2001 Hyundai Elantra with the engine maintenance
light on.  I used a ScanGauge II to find the code.  I got
U0D07.  I reset the car and checked when the light
reappeared with the same code result.  What does this code
indicate?

Thank you!

ANSWER: Hi, Gordon.  U0D07 is not a defined code.  Most likely your code reader is not communicating properly with your vehicle.  Perhaps try to see if you can get your local AutoZone or AAMCO to read your trouble code for free and report the results back.

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QUESTION: Advance Auto read the code as P0507.  Any suggestions?

Thank you!

Answer
P0507 indicates RPM higher than expected; i.e. the idle actuator cannot control the idle speed.

Look first for vacuum leaks, especially in the hose between the intake and PCV valve.  Also check to see if you have an intake manifold gasket leak; this is often accompanied by a misfire at idle.

If no vacuum leaks are present, I'd only then be looking toward the idle actuator as a probably cause.  Idle actuator failures are rare on this vehicle.