1996 Bronco 401 Code
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Fleet Mechanic
Joined: Dec 2006
Posts: 1,388
Likes: 6
1996 Bronco 401 Code
Getting the dreaded 401 code on my 1996 bronco 351w and have tried just about everything I can think of.
List contains:
New EGR
New DPFE
New Vacuum lines
New Vacuum canister
What am I missing?
Bronco starts with high idle and sometimes stalls but after she warms up bronco runs like a dream.
Note:
Exhaust system has been cut right after the muffler and I am wondering if that will limit the back pressure and cause 401 code? Also had oem y pipe modified to fit around aftermarket oil pan and might have some exhaust leaks.
Thanks.
List contains:
New EGR
New DPFE
New Vacuum lines
New Vacuum canister
What am I missing?
Bronco starts with high idle and sometimes stalls but after she warms up bronco runs like a dream.
Note:
Exhaust system has been cut right after the muffler and I am wondering if that will limit the back pressure and cause 401 code? Also had oem y pipe modified to fit around aftermarket oil pan and might have some exhaust leaks.
Thanks.
Fleet Owner
Joined: Oct 2005
Posts: 20,789
Likes: 1,753
From: Kentucky
The OP has a 1996 model which is OBD-II. Code "401" is actually P0401: Exhaust Gas Recirculation Flow Insufficient Detected.
Fleet Owner
Joined: Oct 2005
Posts: 20,789
Likes: 1,753
From: Kentucky
No a leaking exhaust is not a typical cause of P0401. The EGR tube can become clogged with carbon build up. A very common problem. A cracked EGR tube is a common cause of this code too.
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Fleet Owner
Joined: Oct 2005
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From: Kentucky
You might find this troubleshooting procedure useful for your issue: FORD DPFE SENSOR TEST
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Fleet Mechanic
Joined: Dec 2006
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Replaced dpfe sensor already several weeks back. I am thinking maybe the evp sensor(not sure I got the name right) but sensor is located down stream from the egr vacuum line on my 96. When the vacuum line is pulled off the egr at idle the vacuum is very weak, not sure if that is good or bad indication. Also code po401 usually occurs in stop and go traffic and on the hwy code is non existent. Any thoughts?
Fleet Owner
Joined: Oct 2005
Posts: 20,789
Likes: 1,753
From: Kentucky
Physical inspection is the best way to check for cracks in the EGR tube. The old design with the accordion style section is well know to crack after years of use. Did you replace the silicone hoses leading to the DPFE?
The solenoid/sensor, actually upstream of the EGR, is the EGR Vacuum Regulator (EVR). There should be no vacuum at the EGR when the truck is idling. EGR is only applied under light throttle cruising conditions.
For reference: EVR
The solenoid/sensor, actually upstream of the EGR, is the EGR Vacuum Regulator (EVR). There should be no vacuum at the EGR when the truck is idling. EGR is only applied under light throttle cruising conditions.
For reference: EVR
Thread Starter
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Fleet Mechanic
Joined: Dec 2006
Posts: 1,388
Likes: 6
Physical inspection is the best way to check for cracks in the EGR tube. The old design with the accordion style section is well know to crack after years of use. Did you replace the silicone hoses leading to the DPFE?
The solenoid/sensor, actually upstream of the EGR, is the EGR Vacuum Regulator (EVR). There should be no vacuum at the EGR when the truck is idling. EGR is only applied under light throttle cruising conditions.
For reference: EVR
The solenoid/sensor, actually upstream of the EGR, is the EGR Vacuum Regulator (EVR). There should be no vacuum at the EGR when the truck is idling. EGR is only applied under light throttle cruising conditions.
For reference: EVR
Did not replace silicone hoses yet.
What do u think?
Thanks.
New User
Joined: Oct 2014
Posts: 2
Likes: 0
Getting the dreaded 401 code on my 1996 bronco 351w and have tried just about everything I can think of.
List contains:
New EGR
New DPFE
New Vacuum lines
New Vacuum canister
What am I missing?
Bronco starts with high idle and sometimes stalls but after she warms up bronco runs like a dream.
Note:
Exhaust system has been cut right after the muffler and I am wondering if that will limit the back pressure and cause 401 code? Also had oem y pipe modified to fit around aftermarket oil pan and might have some exhaust leaks.
Thanks.
List contains:
New EGR
New DPFE
New Vacuum lines
New Vacuum canister
What am I missing?
Bronco starts with high idle and sometimes stalls but after she warms up bronco runs like a dream.
Note:
Exhaust system has been cut right after the muffler and I am wondering if that will limit the back pressure and cause 401 code? Also had oem y pipe modified to fit around aftermarket oil pan and might have some exhaust leaks.
Thanks.
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