OK this problem has spread to a great number of mustangs who have either repaired or modified their cars. This effects both 3.7L mustangs and 5.0 Mustangs 2011 and newer.
You must go to the dealer and have them use the IDS computer and reset your ECU. I am calling this the Ford Mustang ECU bug!
I had to take my car to the Ford dealer and they would NOT cover it under warranty. Even though clearly its a Ford Bug. I am very upset with Ford and will continue to bring this issue into the limelight until they make good on it.
21474 – Some vehicles could exhibit misfire codes after certain repairs – multiple vehicle lines some vehicles equipped with on board diagnostics (obd) misfire monitor neutral profile learning capabilities may experience the mil illuminating accompanied by one or more engine misfire codes p030x if the crankshaft position sensor profile (mp_lrn) is not relearned following certain hard engine repairs. The mp_lrn data is no longer cleared with a kam reset or battery disconnect. Repairs that require relearning the mp_lrn data: Crank sensor,crank sensor, trigger wheel, engine timing, damper, crankshaft, engine, flywheel/flexplate, clutch (manual trans), pressure plate (manual trans),torque converter (auto trans). From the ids toolbox select “powertrain”, then “service functions”, then “misfire monitor neutral profile correction” and follow the prompts.
Ssm 21463 2010-2011 5.0l/6.2l – misfire codes p0300-p0316
Some 2011 mustang vehicles equipped with a 5.0l engine and 2010 f150 and 2011 super duty vehicles equipped with a 6.2l engine may exhibit the malfunction indicator lamp illuminating accompanied by one or more diagnostic trouble codes p0300 through p0316. It is recommended that the crankshaft position sensor profile (mp_lrn) be relearned prior to performing the pc/ed pinpoint tests for these codes. From the ids toolbox select “powertrain”, then “service functions”, then “misfire monitor neutral profile correction” and follow the prompts. If one or more of the misfire codes return after performing the relearn procedure, refer to the pc/ed pinpoint tests.
Check this page If you are getting DTC CODE P0019 Error