Engine-Codes - Buick - P0401 Buick

P0401 Buick Code - Exhaust Gas Recirculation Flow Insufficient

- Code Popularity: 30,911 Views
- Repair Importance Level: 2/3
- Repair Difficulty Level: 2/3
Table of contents
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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

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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How to Fix the DTC P0401 Buick?

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 P0401 Buick 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)
  • Engine hesitation

What Does the P0401 Buick Code Mean?

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.
P0401 Buick Code - Exhaust Gas Recirculation Flow Insufficient

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