P1000 is a code for no DTC's found. The P1260 is a bullshit code for theft detected and can be triggered with battery failure.
The P1518 code is for the "Intake Manifold Runner Control" stuck open. This is caused by either the actual part "IMRC" has failed or the intake manifold "butterflies" are clogged up with carbon causing it not to return.
The "IMRC" is a box with a cable on it found on the front valve cover.