What's the p1005 code Chevy silverado?

When You get a check engine light (CEL) error of P1005 on Your Chevy Silverado, this is an ODB-II diagnostic code indicating that there's an issue with the manifold tunning valve control. The P indicates that this is related to Your powertrain, the 1 for the Fuel and Air Metering, and the 5 for the shift solenoid circuit. In plain English, though, this usually means it's possible that Your oxygen sensor has failed or is going to. However, this can also occur because of fuel that failed to properly combust. In this case, if You hook up a scanning tool, or take it to a place like Autozone, where they'll clear the codes for free for You, it often will remain off once removed. Occasionally this can indicate a more serious pre-failure condition for the catalytic convertor, which can cost almost $2k to get fixed. If You're getting this CEL, and it is the sensor, it's pretty easy to sort out Yourself. In any case, it's usually safe to just clear the code and see if it comes back the first time You see it.