The P0640: Intake Air Heater Control Circuit code indicates an issue with the control circuit responsible for the intake air heater, which is typically used in diesel engines to heat the air entering the engine for improved cold-start performance. This error can be caused by a faulty control circuit, wiring issues, or a malfunctioning intake air heater.
P0640 – Quick Overview
| Code | Information |
|---|---|
| Meaning | P0640: Intake Air Heater Control Circuit |
| Is it serious? | Yes, it can affect engine performance, especially during cold starts. |
| Possible causes | – Faulty intake air heater control circuit – Wiring issue – Faulty intake air heater |
| How to diagnose? | – Test intake air heater control circuit – Inspect wiring and connectors – Replace intake air heater if necessary |
P0640 Meaning
The P0640 code indicates that the control module has detected an issue in the intake air heater control circuit. The intake air heater is responsible for heating the air that enters the engine to improve combustion during cold starts, especially in diesel engines. A malfunction in this system can result in poor cold-start performance, rough idling, or increased emissions.
Step-by-step diagnostic guide
| Action | Description | Tools Needed |
|---|---|---|
| Check for Other Codes | Use an OBD-II scanner to check for other related codes, particularly those affecting the intake air system or cold-start functionality. | OBD-II Scanner |
| Test the Intake Air Heater Control Circuit | Use a multimeter to check the voltage and continuity of the intake air heater control circuit to ensure it is functioning within specification. | Multimeter |
| Inspect Wiring and Connectors | Inspect the wiring and connectors leading to the intake air heater for signs of damage, loose connections, or corrosion. | Flashlight, Multimeter |
| Test the Intake Air Heater | If the control circuit appears fine, test the intake air heater itself to ensure it is heating the air properly during startup. | Diagnostic Tool, Multimeter |
| Replace the Intake Air Heater if Necessary | If the intake air heater is faulty and not providing adequate heating, replace it to restore proper engine performance during cold starts. | Replacement Heater, Tools |
| Clear the Code and Test | After repairs, clear the code using an OBD-II scanner and test the vehicle to ensure the intake air heater system is functioning correctly. | OBD-II Scanner, Vehicle Manual |
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Hi, I am Juraj “Yuri” Lukacko. I got frustrated by unhelpful and scammy mechanics, so I decided to learn everything about car diagnostics myself. I test dozens of new car diagnostic tools every month along with learning new strategies to fix and customize cars. About Juraj Lukacko (Yuri)