Check the 'Possible Causes' listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
The cost to diagnose the P1257 GMC code is 1.0 hour of labor. The diagnosis time and labor rates at auto repair shops vary depending on the location, make and model of the vehicle, and even the engine type. Most auto repair shops charge between $75 and $150 per hour.
With the engine running, the Intake Air Temperature (IAT) sensor input more than 14°F, then the Powertrain Control Module (PCM) detects that the engine torque was above a maximum threshold value (value vanes by commanded gear and rpm) for 6 seconds.
Need more information on how to fix the P1257 GMC code? Get Access to Factory Service Manuals
Get the P1257 GMC code diagnosed by a professional: Find a repair shop in your area