What does it mean?
P1512 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Intake Manifold Changeover Valve Circuit Short to B+ .
Symptoms
- Check engine light on with normal idle quality
- Torque loss either at low rpm or at high rpm because the changeover valve stays in one position
- Acceleration feels flat through part of the rev range
- Constant buzzing from the vacuum solenoid in some layouts
- Small rise in fuel consumption
- No other warning lamp behaviour
Likely causes
- Control wire shorted to a positive feed where the insulation has rubbed or melted
- Corrosion inside the changeover valve connector bridging the supply and control pins
- Internal short in the valve winding to its supply side
- Harness damaged during previous work on the intake manifold or the ignition coils
- Aftermarket wiring tapped into or routed against the valve circuit
- Module driver that can no longer pull the circuit low
How to fix it
- Unplug the changeover valve, switch the ignition on with no command and measure the control pin to ground; battery voltage confirms a short to positive
- Unplug the module connector as well; if the voltage remains, the fault is in the harness
- Inspect the harness where it crosses power feeds, ignition coils and hot components
- Measure the winding resistance and check for leakage between the valve terminals and its body
- Clean or replace a corroded connector and repair the damaged harness section
- Replace the changeover valve if it shows an internal short
- Actuate the valve with a scan tool afterwards and verify the flap moves fully