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Old 02-06-2003, 11:45 AM   #1
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Default Code 401

Long story, short........a friend of mine has a Chevy Lumina with a check engine light on........the mechanic told her it was a code 401, but did not explain........any one help me with this ??

Thanks....DD
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Old 02-06-2003, 12:05 PM   #2
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Sorry.........friend said it read 0401 code not just 401 if that makes a difference....she did not say that the first time, I swear some need to stick to just driving and putting gas in...

Thanks..........
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Old 02-06-2003, 02:08 PM   #3
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EGR flow insufficient. Since it'* a 4-digit code, she'* OBD2, and she probably has the linear EGR valve.
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Old 02-06-2003, 02:09 PM   #4
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Damn. We were writing that at the same time. He beat me.
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Old 04-20-2005, 02:52 AM   #5
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Default p0401 code set due to pcv valve... believe it or not

i finally solved the problem with the P0401 CODE on my 97 bonneville 3800 vin K

believe it or not, it was caused by the repair shop leaving the PCV valve out when they changed the upper plenum...

it sits directly below the MAP sensor... they swapped the plenum and left the PCV valve in the old part... it caused the code to set...

i found out, that code is more about the MAP SENSOR'* ability to sense pressure change in the intake manifold when the egr valve is commanded on by the computer, than whether egr gasses are flowing or not...

since the pcv valve was missing, the MAP SENSOR was sensing no change in the intake manifold pressure, which told it the egr wasn't flowing... but it was really the fact that the PCV VALVE wasnt allowing the manifold pressure to build to a point that it could drop when the egr opened.... this in turn sent a false signal to the MAP SENSOR...

all over a missing PCV VALVE...
now a faulty one, (sticking open) could cause the same problem....

hope this helps you...

check or replace the PCV VALVE cheap insurance for less than $5 bucks..
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Old 04-20-2005, 02:55 AM   #6
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Please don't dig up topics that are old. This was back in 2003.
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