What does it mean?
P1507 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Idle Air Control Valve Circuit Short to Ground .
Symptoms
- Check engine light on with an idle that will not settle
- Idle either stuck high or dropping and stalling, depending on the valve position when it locked
- Engine stalls on deceleration and is hard to restart immediately
- No idle-up under electrical or A/C load
- In some layouts the fuse feeding the idle circuit blows repeatedly
- Poor drivability just off idle, with a stumble on light throttle
Likely causes
- Control wire rubbed through against the cylinder head, a bracket or a clamp
- Shorted winding inside the idle air control valve
- Water or coolant intrusion in the valve connector
- Harness pinched during previous work on the intake or throttle body
- Wire damaged by rodents or by lost heat shielding near the exhaust side
- Module driver failed in the shorted state, holding the output permanently low
How to fix it
- Unplug the valve and measure the control wire to ground; low resistance with the connector open confirms a harness short
- Disconnect the module connector as well; if the short remains, the fault is in the harness, not the module
- Measure the valve winding resistance and also from each terminal to the valve body to find an internal short
- Follow the harness along the head, brackets and clamps looking for the rub point
- Check the connector for water and clean or replace a corroded one
- Repair or reroute the damaged harness section, then clear the code and watch idle in live data
- Replace the valve if it is internally shorted, and treat the module as the final suspect