AutoCodes – Buick – P0490 Buick

P0490 Buick Code - Exhaust Gas Recirculation Motor Control Circuit High Voltage

Quick Answer

The Engine Control Module (ECM) supplies the Exhaust Gas Recirculation (EGR) valve with a 5 V reference circuit, a low reference circuit, an H-bridge motor directional control circuit, and a signal circuit. Common causes include Faulty Exhaust Gas Recirculation (EGR) Valve, Exhaust Gas Recirculation Valve harness is open or shorted, Exhaust Gas Recirculation Valve circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0490 Buick indicates Exhaust Gas Recirculation Motor Control Circuit High Voltage.
Common causes: Common causes include Faulty Exhaust Gas Recirculation (EGR) Valve, Exhaust Gas Recirculation Valve harness is open or shorted, Exhaust Gas Recirculation Valve circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 669

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 24, 2024

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0490 Buick Description

The Engine Control Module (ECM) supplies the Exhaust Gas Recirculation (EGR) valve with a 5 V reference circuit, a low reference circuit, an H-bridge motor directional control circuit, and a signal circuit. The EGR position sensor provides a signal voltage that changes relative to the EGR position. The EGR position sensor information is transmitted between the EGR valve and the ECM on the signal circuit. The Mass Air Flow (MAF) sensor signal is used by the ECM to detect the proper amount of EGR flow. The ECM will close the EGR valve, then open the EGR valve to 100%. The ECM will then calculate the MAF difference and determine if the proper EGR flow has been detected. The Diagnostic Trouble Code (DTC) will be set when the ECM detects a short to voltage on the control circuit for greater than 2.5 s.

OBDII Code P0490 Buick - Exhaust Gas Recirculation Motor Control Circuit High Voltage - AutoCodes.com — P0490 Buick Code - Exhaust Gas Recirculation Motor Control Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P0490 Buick?

Faulty Exhaust Gas Recirculation (EGR) Valve
Exhaust Gas Recirculation Valve harness is open or shorted
Exhaust Gas Recirculation Valve circuit poor electrical connection
Faulty Engine Control Module (ECM)

How to Fix the DTC P0490 Buick?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0490 Buick code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P0490 Buick code?

Need more information on how to fix the P0490 Buick code? Get Access to Factory Service Manuals

Need Help with the Code?

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0490 Buick Code

1. What are common symptoms of OBDII code P0490 in a Buick?

- Common symptoms include the check engine light illuminating, reduced engine performance, rough idling, and potential stalling.

2. What does the OBDII code P0490 indicate in a Buick?

- The code P0490 indicates a high voltage condition in the exhaust gas recirculation (EGR) motor control circuit of the vehicle.

3. What are potential causes of OBDII code P0490 in a Buick?

- Potential causes may include a faulty EGR valve, a malfunctioning EGR motor, damaged wiring or connectors in the EGR circuit, or a problem with the EGR control module.

4. How can I diagnose the OBDII code P0490 in my Buick?

- Diagnosing code P0490 typically involves inspecting the EGR system components, checking for damaged wiring or connectors, testing the EGR motor, and scanning for any related trouble codes.

5. Can I still drive my Buick with OBDII code P0490 present?

- It is not recommended to drive your Buick with code P0490 present, as it can lead to further engine damage and potential safety issues. It's best to address the underlying problem promptly.

6. How can I repair OBDII code P0490 in my Buick?

- Repair options may include replacing the EGR valve, repairing or replacing damaged wiring or connectors, testing and replacing the EGR motor, or addressing any issues with the EGR control module.

7. Is it safe to reset the OBDII code P0490 in my Buick using a diagnostic tool?

- While you can reset the code using a diagnostic tool, it is crucial to address the underlying issue causing code P0490 to prevent further damage to your Buick's engine.

8. Will OBDII code P0490 cause my Buick to fail an emissions test?

- Yes, code P0490 can cause your Buick to fail an emissions test due to the malfunction in the EGR system affecting the vehicle's emissions control.

9. How much does it typically cost to repair OBDII code P0490 in a Buick?

- The cost of repairing code P0490 can vary depending on the specific issue causing the code, but it may range from $200 to $600 or more, including parts and labor.

10. Can I prevent OBDII code P0490 from occurring in my Buick?

- Regular maintenance, such as cleaning the EGR system components, checking for any signs of wear or damage, and addressing issues promptly can help prevent code P0490 from occurring in your Buick.