P0401 Buick - Exhaust Gas Recirculation Flow Insufficient
- EGR passage clogged
- Faulty EGR Valve
- EGR solenoid valve harness is open or shorted
- EGR solenoid valve circuit poor electrical connection
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.
When is the code detected?
The Powertrain Control Module (PCM) sets a DTC P0401 when the fail counter exceeds the fail threshold. The number of test samples required to exceed the fail threshold varies according to the magnitude of the detected flow errors.
- Engine Light ON (or Service Engine Soon Warning Light)
- Possible engine hesitation
P0401 Buick Description
The Powertrain Control Module (PCM) tests the EGR system during deceleration by momentarily commanding the EGR valve open. The pressure in the intake manifold increases when the EGR valve is open. The PCM monitors the Manifold Absolute Pressure (MAP) sensor signal during the EGR system diagnostic in order to determine the amount of EGR flow. The PCM calculates an error based on the difference between the actual MAP increase and a predetermined value. The PCM records the error and adjusts an internal fail counter towards the fail threshold if the error is too great.
Need more help?
Do you need more help with the P0401 Buick code? ask a question to our users or search the top hand picked automotive forums for more information
Repair Shops Around Your Area
Need parts to fix this code? Search hundreds of stores at the same time and compare prices
Help us improve Engine-Codes.com. Leave a comment below or tell us if the information above help you fix the code. What are symptoms is your vehicle for the P0401 Buick code? Have you replaced any parts?
Any information is appreciated. Thanks