Engine-Codes - Generic - P0640

P0640 Code - Intake Air Heater 'A' Control Circuit

- Code Popularity: 13,306 Views
- Repair Importance Level: 3/3
- Repair Difficulty Level: 2/3
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What are the Possible Causes of the DTC P0640?

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other 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
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How to Fix the DTC P0640?

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.

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What is the Cost to Diagnose the Code?

Labor: 1.0

The cost to diagnose the P0640 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.

What are Code Possible Symptoms?

  • Engine Light ON (or Service Engine Soon Warning Light)

What Does the P0640 Code Mean?

The 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.

P0640 Code - Intake Air Heater 'A' Control Circuit

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Code P0640 Information for Specific Makes

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