P1503 OBD Code Definition:
P1503 Idle Speed Control Valve Closing Solenoid Control Circuit Signal Low
P1503 OBD Code Description:
Possible Causes
- Alternator faulty
- Voltage Regulator faulty
- Wiring and/or connections faulty
Possible Solutions
- Check / Replace Alternator
- Check / Replace Voltage Regulator
- Check wiring and connections
- Check the fuse box that is in the battery tray, it might be burnt, the fuse or the complete plastic box (pretty common failure on Sharan because it carries so much electrical load). If so, change the complete fuse box, it is not too expensive fix if this is the cause.
Special Notes
- When found on the BEW engine, check MVB 16, Field 1. In most cases values will be between 15% to 30% at idle. 0% could indicate a failed or incorrect alternator.