Saturday, May 14, 2011

OBD-II Trouble Code: P0401 Insufficient EGR Flow on a 2003 GrandAm

EGR stands for exhaust gas recirculation. If you look at the EGR valve, you will see that the inlet is connected to a metal hose connected to your exhaust pipe. The outlet is connected to a small hole on your engine. Apparently, allowing exhaust back into the engine improves efficiency. This is probably because there is unburnt fuel in the exhaust. If your Check Engine light illuminates and you read a P0401 OBD code, the system is telling you that the exhaust flow back into your engine is restricted. This can be due to a faulty EGR valve or the path of the flow is blocked.
  1. Test the EGR valve. Remove it and apply voltage across the pins with a 9-volt battery. You should hear the solenoid click. If not, the EGR value need to be replaced. More information on which pins to connect for the test can be found here. In most cases, the EGR valve is still functional.
  2. The intake into the engine tends to clog. Remove the rubber air duct connected to the engine. This should give you access to intake hole. This intake hole is in direct contact with the outlet of the EGR valve. A clogged intake hole will be obvious as indicated by the carbon buildup. Spray some carburetor cleaner on the buildup and wait a couple of hours. The carbon buildup will dissolve. Wipe clean and reconnect everything.
If you have solved the problem, you don't have to reset the Check Engine light. After driving the vehicle a couple of times, the light should deactivate automatically.

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