What does it mean?
P1490 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Evaporative Emission System Purge Control Valve Circuit Low .
Symptoms
- MIL on
- Purge valve held open, giving a rough idle and stalling shortly after start up
- Fuel trims swing rich or lean at idle as unmetered vapour enters the intake
- Fuel vapour odour around the engine bay
- Difficult starting immediately after refuelling
- EVAP monitor stays incomplete
Likely causes
- Purge valve control circuit shorted to ground
- Purge solenoid coil shorted internally
- Harness chafed and grounding against the engine or a bracket
- Corrosion bridging pins inside the purge valve connector
- Wiring damaged during previous intake manifold or engine work
- Module driver stuck low, or damaged by an earlier short
How to fix it
- Unplug the purge valve and see whether idle quality improves, which points to a valve held open
- With the valve disconnected, measure resistance from the control wire to ground
- Measure the solenoid coil resistance to find an internal short
- Inspect and repair chafed harness sections near the intake
- Check that the valve seals fully when closed using a hand vacuum pump
- Replace the purge solenoid if it leaks through or tests shorted
- Clear the code and confirm normal idle quality and stable fuel trims