Misfire Error Codes & Check Engine Light
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Member
Joined: Apr 2013
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hey guys,
So i was just out for a drive and was keeping an eye on the computer and I have a pending P0401 - Insufficient EGR Flow. Does this provide any more clues as to what the problem may be? In a worst case I will bring it to a shop if I can't figure it out but I'm thinking most of these things can be diagnosed and fixed by myself and with your help.
Thank you.
So i was just out for a drive and was keeping an eye on the computer and I have a pending P0401 - Insufficient EGR Flow. Does this provide any more clues as to what the problem may be? In a worst case I will bring it to a shop if I can't figure it out but I'm thinking most of these things can be diagnosed and fixed by myself and with your help.
Thank you.
Senior Member
Joined: Jul 2004
Posts: 6,200
Likes: 39
From: Easton, Pa.
EGR = exhaust gas recirculation.
A metal tube from the driver side exhaust manifold goes to the EGR valve up at the intake near the throttle body.
Inside this tube is a restriction.
A sensor called the DPFE is connected across the restriction to measue flow rate when tested.
The flow is from the exhaust manifold to the intake when the EGR is opened a small amount.
If this flow is absent or to low, a 401 code is set telling you of the failure.
WHAT COULD BE THE PROBEM?
1. The ports behind the EGR are blocked stopping the flow.
2. The EGR is faulty.
3. The vacuum regulator that applies intake vacuum to the EGR is faulty.
4. The DPFE sensor is faulty.
5. Any connecting hoses faulty.
How to test for blocked flow.
1. Apply vacuum to the EGR as the way to open it a small amount while the motor is at idle.
If the passage is NOT blocked, the motor will begin to run rough. This is normal.
If no difference, the EGR should be removed for passage check behind it or the EGR will not open when vacuum is applied and is faulty.
No issue found leaves the DPFE the last part to be suspect.
.
You see it's nessesary to understand how things work in order to tell when something is wrong.
Code only give's you a lead to the total system involved.
BTW, EGR only operates in OD above 45 mph at light throttle openings but could operate in third gear at light throttle if OD is locked out.
All this is controlled by the computer.
Good luck. and god i hope i'm forgiven!
A metal tube from the driver side exhaust manifold goes to the EGR valve up at the intake near the throttle body.
Inside this tube is a restriction.
A sensor called the DPFE is connected across the restriction to measue flow rate when tested.
The flow is from the exhaust manifold to the intake when the EGR is opened a small amount.
If this flow is absent or to low, a 401 code is set telling you of the failure.
WHAT COULD BE THE PROBEM?
1. The ports behind the EGR are blocked stopping the flow.
2. The EGR is faulty.
3. The vacuum regulator that applies intake vacuum to the EGR is faulty.
4. The DPFE sensor is faulty.
5. Any connecting hoses faulty.
How to test for blocked flow.
1. Apply vacuum to the EGR as the way to open it a small amount while the motor is at idle.
If the passage is NOT blocked, the motor will begin to run rough. This is normal.
If no difference, the EGR should be removed for passage check behind it or the EGR will not open when vacuum is applied and is faulty.
No issue found leaves the DPFE the last part to be suspect.
.
You see it's nessesary to understand how things work in order to tell when something is wrong.
Code only give's you a lead to the total system involved.
BTW, EGR only operates in OD above 45 mph at light throttle openings but could operate in third gear at light throttle if OD is locked out.
All this is controlled by the computer.
Good luck. and god i hope i'm forgiven!