P0640 GMC - Intake Air Heater 'A' Control Circuit
P0640 GMC Possible Causes
- Faulty Intake Air Heater (IAH) Relay
- Faulty Intake Air Heater
- Intake Air Heater Relay harness is open or shorted
- Intake Air Heater Relay circuit poor electrical connection
- Intake Air Heater harness is open or shorted
- Intake Air Heater circuit poor electrical connection
How do I fix code P0640 GMC?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's pins.
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Cost of diagnosing the P0640 GMC code
Labor: 1.0The cost of diagnosing the P0640 GMC code is 1.0 hour of labor. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour.
- Engine Light ON (or Service Engine Soon Warning Light)
P0640 GMC DescriptionThe Engine Control Module (ECM) uses an Intake Air Heater (IAH) to warm the incoming air for proper cylinder combustion. The ECM grounds the control coil of the IAH relay to energize the heater during cold operation. The control module will command the IAH ON when the engine coolant temperature is below 40 C (104 F). The power to the IAH heater is supplied by the battery positive voltage circuit through the IAH relay.
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