2005 SV6 Reduced Engine Power

[ChrisG]

I have a 2005 SV6. when it is cold outside the engine light comes on then Reduced Engine Power comes up on the display. After letting the van warm up to operating temp. I shut it off then restart. Engine light stays on but van is no longer in Reduced Engine Power mode and I can drive it.
I get the following codes: p1516, p2101 and p2135.
Any help would be greatly appreciated.

 

[melsg5]

All the codes refer to a throttle problem. Your vehicle does not use a cable to open the throttle it has TAC, throttle activator control module. This repair requires a scan tool capable of diagnosing where the issue is in the system. The two Chevy codes apply to Pontiac also.
http://www.obd-codes.com/p2135
http://engine-codes.com/p1516_chevrolet.html
http://engine-codes.com/p2101_chevrolet.html