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P0401 Buick Code - Exhaust Gas Recirculation Flow Insufficient

- Code Popularity: 30,910 Views
- Repair Importance Level: 2/3
- Repair Difficulty Level: 2/3
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What are the Possible Causes of the DTC P0401 Buick?

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
  • Exhaust Gas Recirculation (EGR) passage clogged
  • Faulty EGR Valve
  • EGR solenoid valve harness is open or shorted
  • EGR solenoid valve circuit poor electrical connection
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How to Fix the DTC P0401 Buick?

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

Code Tech Notes

The EGR flow malfunction could be caused by a clogged EGR valve or EGR tube. Before replacing any parts try cleaning the EGR valve, tube, and passages.

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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0401 Buick code, it typically requires 1.0 hour of labor. The specific diagnosis time and labor rates at auto repair shops can differ based on factors such as the location, make and model of the vehicle, and even the engine type. It is common for most auto repair shops to charge between $75 and $150 per hour.

What are Code Possible Symptoms?

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

Code P0401 Buick Description

The Exhaust Gas Recirculation (EGR) valve is controlled by the Engine Control Module (ECM). The ECM controls the EGR valve by supplying a 12-volt pulse width modulated signal to the EGR Valve low control circuit and 12 volts to the high control circuit. The ECM monitors the EGR flow performance when the EGR is active by comparing the desired Mass Air Flow (MAF) to the actual MAF. If the difference between the desired MAF and the actual MAF is less than or greater than a calibrated threshold level the amount of detected EGR flow is out of range. The Diagnostic Trouble Code (DTC) will be set when the ECM detects that the difference between the desired mass airflow and the actual mass air flow is less than a calibrated value for greater than 12.5 s.
OBDII Code P0401 Buick - Exhaust Gas Recirculation Flow Insufficient - AutoCodes.com
P0401 Buick Code - Exhaust Gas Recirculation Flow Insufficient

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Code P0401 Buick comments

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