The P0490: Exhaust Gas Recirculation ‘A’ Control Circuit High refers to a high voltage issue within the EGR (Exhaust Gas Recirculation) control circuit. This can be caused by a faulty EGR control circuit, excessive voltage supply, or wiring problems. The code suggests that the EGR system is not functioning correctly, which can impact engine performance and emissions.
P0490 – Quick Overview
| Meaning | P0490: Exhaust Gas Recirculation ‘A’ Control Circuit High |
| Is it serious? | Yes, this code can lead to improper exhaust gas recirculation, which may affect engine efficiency and increase emissions. |
| Possible causes | – Faulty EGR control circuit – High voltage supply – Wiring issues |
| How to diagnose? | – Test the EGR control circuit for high input – Verify voltage supply to the circuit – Inspect wiring for shorts or damage |
P0490 Meaning
The P0490: Exhaust Gas Recirculation ‘A’ Control Circuit High means that the EGR control circuit is receiving too much voltage, which may prevent the exhaust gas recirculation system from operating correctly. This can result in poor emissions control, reduced fuel efficiency, and potential engine performance issues. The problem could stem from a faulty control circuit, an excessive voltage supply, or wiring issues within the system.
Step-by-step diagnostic guide
Follow the outlined procedure to diagnose this DTC by eliminating possible causes one by one.
| Action | Description | Tools Needed |
|---|---|---|
| Check for Other Codes | Use an OBD-II scanner to check if there are any other related codes present. These might give additional clues about the problem. | OBD-II Scanner |
| Inspect the EGR Control Circuit | Visually inspect the EGR control circuit for any signs of damage, corrosion, or disconnection. Ensure the circuit is properly connected. | Flashlight, Safety Gloves |
| Test the EGR Control Circuit | Use a multimeter to test the EGR control circuit for high input voltage. Compare the readings to the manufacturer’s specifications. | Multimeter, Manufacturer’s Specifications |
| Check Voltage Supply | Verify that the voltage supply to the EGR circuit is within the correct range. Excessive voltage could trigger this code. | Multimeter |
| Inspect Wiring and Connectors | Carefully inspect the wiring and connectors leading to the EGR control circuit for signs of wear, corrosion, or shorts. Repair or replace as necessary. | Flashlight, Multimeter |
| Clear the Code and Test Drive | After completing the necessary repairs, clear the P0490 code using the OBD-II scanner. Take the vehicle for a test drive to ensure the issue is resolved and the code does not return. | OBD-II Scanner, Vehicle Owner’s Manual |
| Recheck for Codes | After the test drive, re-scan the vehicle to ensure the P0490 code has not reappeared. If the code returns, further diagnosis may be required. | OBD-II Scanner |
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I test OBD-II scanners and make DIY Engine diagnostics guides to help you solve your car problems without having to depend on the mechanic. A lot of them will try to scam you or are just no help at all. About Juraj Lukacko