P0507

P0507 sets when actual idle RPM exceeds target by 200 RPM or more with the IAC commanded fully closed, meaning the engine is getting more air than it should at idle. It is the second most-searched idle code and the cause hierarchy is well-established: vacuum leak first (roughly 60 percent of cases), dirty throttle body or IAC second (25 percent), TPS adaptation needing reset third (10 percent), and actual sensor/valve failure last. Cheapest-first diagnosis: smoke-test the intake from the throttle body to the valve covers, looking at PCV, brake booster, EVAP purge, intake manifold gasket sealing surfaces, and any cracked vacuum lines. A leak as small as 0.5 mm at the brake booster hose will lift idle by 200 to 400 RPM. With no leak found, scan IAC steps at warm idle, a P0507 vehicle reads 0 steps with elevated RPM, which means the IAC has zero authority left and the air is bypassing it. Clean the throttle body, inspect the throttle plate for a stuck-open condition, and run the manufacturer's idle relearn. On drive-by-wire vehicles, this code becomes a throttle-adaptation reset task instead. The expensive misdiagnosis is replacing the throttle body assembly when a $4 vacuum cap or a $12 PCV grommet fixes it.

Vehicle-specific patterns: 1999 to 2007 GM 4.8L/5.3L/6.0L Vortec sets P0507 from cracked PCV hoses or a leaking upper intake gasket, same TSB 06-06-04-037 as P0506. 2002 to 2008 Subaru EJ25 (Outback, Forester, Legacy) sets P0507 after throttle body cleaning if you skip the idle/throttle relearn procedure, Subaru TSB 11-110-09 covers the relearn (key on, accelerator pedal cycles, 10-minute idle stabilization). 2005 to 2014 VW/Audi 2.0T (EA113 and EA888) sets P0507 from a carbon-fouled throttle body and requires a throttle adaptation via VCDS or OBDeleven (basic settings, channel 060 or 098 depending on ECU). 2003 to 2009 Toyota 1MZ-FE and 2GR-FE V6 (Camry, Highlander, Sienna) sets P0507 from a sticking ETC throttle plate, Toyota TSB EG009-09 covers the throttle body cleaning and relearn. Estimated repair: $20 to $480.