What causes gm trouble codes PO 125 and PO 338?

GM trouble code P0125 indicates an insufficient coolant temperature for closed-loop operation, often caused by a faulty thermostat, a malfunctioning coolant temperature sensor, or low coolant levels. Code P0338 relates to a problem with the crankshaft position sensor circuit, which can result from a faulty sensor, poor wiring, or a bad connection. Both codes can lead to engine performance issues and should be diagnosed to prevent further damage.