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 P1639 Chevrolet 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.
If the voltage is out of tolerance, the Powertrain Control Module (PCM) will set DTC P1639.
The Powertrain Control Module (PCM) uses the 5-volt reference 2 circuit as a sensor feed for the A/C refrigerant pressure sensor. The PCM monitors the voltage on the 5-volt reference 2 circuit.
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