not had it but wiki says
16891/P0507/001287 - Idle Control System RPM: Higher than Expected.
Possible Symptoms
* Malfunction Indicator Lamp (MIL) active
Possible Causes
* Throttle Valve Control Module (J338) dirty/faulty
* Wiring/Connector(s) from/to Throttle Valve Control Module (J338)
Possible Solutions
* Check Throttle Valve Control Module (J338)
* Check Wiring/Connector(s) from/to Throttle Valve Control Module (J338)