What does it mean?
P1515 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Intake Manifold Changeover Valve Circuit Short to Ground .
Symptoms
- Check engine light on with an otherwise smooth-running engine
- Manifold flap held in one position, so torque drops in part of the rev range
- Dull acceleration where the manifold should change over
- In some layouts the fuse feeding the valve blows repeatedly
- Small increase in fuel consumption
- Idle and cold starting stay normal
Likely causes
- Control wire rubbed through against the manifold, a bracket or a clamp
- Water or coolant intrusion into the valve connector
- Shorted winding inside the changeover valve
- Harness pinched during earlier work on the intake or ignition system
- Wire damaged by heat where it passes close to the exhaust side
- Module driver failed in a permanently low state
How to fix it
- Unplug the valve and measure the control wire to ground; low resistance with the connector open confirms a harness fault
- Disconnect the module connector as well to rule the module in or out
- Measure the winding resistance and the resistance from each terminal to the valve body
- Follow the harness along the manifold and brackets looking for the rub point
- Check the connector for moisture and corrosion and replace it if the terminals are damaged
- Repair or reroute the harness, or replace the changeover valve if it is internally shorted
- Clear the code, actuate the valve with a scan tool and confirm the flap travels fully