P0401 EGR fault but engine lite is still on
Thread Starter
Junior Member
Joined: Aug 2012
Posts: 15
Likes: 0
E320 Avantgarde 3.2ltr W211
P0401 EGR fault but engine lite is still on
Good afternoon all,
On my W211 (2005) Mercedes, I had an EGR fault with P0401 and engine light on. I've bought a new EGR and fitted into the car and for first it was all fine however later the next day the engine light came back on. I am not sure what else to check.
I also have a boom boom sound when car is driving but I cannot identify what it is.
Last problem is, while the car is driving it gives judder
Please help.
Kindedst regards
J.
On my W211 (2005) Mercedes, I had an EGR fault with P0401 and engine light on. I've bought a new EGR and fitted into the car and for first it was all fine however later the next day the engine light came back on. I am not sure what else to check.
I also have a boom boom sound when car is driving but I cannot identify what it is.
Last problem is, while the car is driving it gives judder
Please help.
Kindedst regards
J.
Member
Joined: Oct 2014
Posts: 101
Likes: 8
From: Los Angeles
2005 E500 AMG Appearance Pkg
Could be your o2 sensors or something clogging the intake chamber restricting the amount of exhaust gas going through it. Hook it up to MBII and read the real time data and post any related information here. To be honest I wouldnt know how to exactly decipher the data in regards to your problem but I am sure there are people who use this forum that do. Also if you already changed the EGR valve and are having a boom boom sound (that is probably more like an engine knocking sound) and the engine shakes while driving you may be dealing with engine misfires that can be related to the P0401 code but since you replaced the valve: you likely have a vacuum leak, spark plug issue, carbon build up clogging the intake, damaged o2 sensor...
If not one of these and it probably is the list gets pretty grim pretty fast from my experience. I would get an MBII if you don't already have one.
Try taking off the engine oil cap while the engine is on if its under pressure you have a vacuum leak at the very least. Insufficient (too rich or lean) oxygen ratios in regards to combustion can cause engine knock/misfires. Take a look at your spark plugs, then maybe consider Sea Foam but not before you rule out everything else. Seafoam is effective but controversial to say the least among benz owners.
If not one of these and it probably is the list gets pretty grim pretty fast from my experience. I would get an MBII if you don't already have one.
Try taking off the engine oil cap while the engine is on if its under pressure you have a vacuum leak at the very least. Insufficient (too rich or lean) oxygen ratios in regards to combustion can cause engine knock/misfires. Take a look at your spark plugs, then maybe consider Sea Foam but not before you rule out everything else. Seafoam is effective but controversial to say the least among benz owners.
Thread Starter
Junior Member
Joined: Aug 2012
Posts: 15
Likes: 0
E320 Avantgarde 3.2ltr W211
Thank you for your quick reply and apologies for the delay. I had a new egr but the engine light was still on so I took it to the local garage and they showed the following code
2527 - Check component Y27/9 (Left EGR positioned) signal wire open circuit
2025 - Check component B28/5 (Pressure sensor downstream of air cleaner) The signal voltage is too low
2355 - Check system Exhaust gas recirculating control The air mass is too large
2089 - Check component B60 (Exhaust back pressure sensor ) Voltage is too low.
I already bought and got the exhaust pipe (original from Mercedes) replaced but the above was coming while new EGR was in place. So we replaced the original one in and the car did exactly the same.
kindest regards
J.
2527 - Check component Y27/9 (Left EGR positioned) signal wire open circuit
2025 - Check component B28/5 (Pressure sensor downstream of air cleaner) The signal voltage is too low
2355 - Check system Exhaust gas recirculating control The air mass is too large
2089 - Check component B60 (Exhaust back pressure sensor ) Voltage is too low.
I already bought and got the exhaust pipe (original from Mercedes) replaced but the above was coming while new EGR was in place. So we replaced the original one in and the car did exactly the same.
kindest regards
J.
