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OBDII Code P0400 ?

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Old Mar 29, 2003 | 11:07 PM
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OBDII Code P0400 ? - Problem Solved...Update.

OBDII Code P0400 Exhaust Gas Recirculation Flow Malfunction, anyone had this fault before? Any suggested as to what to check would be appreciated. EGR "plunger" Valve seems to work under vacuum. Thanks...

1996 S320

Last edited by EdS320; Apr 3, 2003 at 11:28 PM.
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Old Mar 30, 2003 | 03:05 AM
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Old Mar 31, 2003 | 12:20 AM
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Old Mar 31, 2003 | 02:54 PM
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P0400 = EGR code..Perform a Test on the EGR valve ..Its Probably the EGR Pipe is Plugged from the EGR Valve to the Intake..
Remove the Metal line and Clean It Out..
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Old Mar 31, 2003 | 07:43 PM
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Old Apr 1, 2003 | 12:23 AM
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Originally posted by MARK CUMMINS
P0400 = EGR code..Perform a Test on the EGR valve ..Its Probably the EGR Pipe is Plugged from the EGR Valve to the Intake..
Remove the Metal line and Clean It Out..
I second that
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Old Apr 3, 2003 | 03:21 AM
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I erased the OBDII code, light is off and waiting to see if it comes back on. Came on the day after I changed the oil? Light came back on with code P0411 Air Pump...
quote:
--------------------------------------------------------------------------------
Originally posted by MARK CUMMINS
P0400 = EGR code..Perform a Test on the EGR valve ..Its Probably the EGR Pipe is Plugged from the EGR Valve to the Intake..
Remove the Metal line and Clean It Out..
--------------------------------------------------------------------------------

Thanks...

Last edited by EdS320; Apr 3, 2003 at 11:45 PM.
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Old Apr 3, 2003 | 11:27 PM
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Solved the problem after removing the EGR which was fine and not blocked. Also Air Pump whine post...After changing the oil I wiped some grease from an electrical connector at the front of the engine, behind the wiring was plastic vacuum tubing that supplies vacuum to the EGR and Secondary Air Pump nest to the EGR Valve by way of the electric solenoids vacuum valves at the front left of the engine. I had inadvertently broken the BRITTLE vacuum tubing, thus killing the vacuum to the solenoids. I put in a rubber vacuum tube splice to reconnect the line ends.

*CAREFUL when you work with or around the tan colored vacuum tubing, as it ages it gets VERY BRITTLE and will break at the slightest bend or pressure. The same tubing runs next to the spark plugs and coils under the engine top cover. If it does break on you, you can use small diameter rubber tubing to reconnect the broken ends together.
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Old Oct 9, 2004 | 03:15 PM
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From: west palm beach fl
98 ml320
98 ml320 egr valve tube

how do you replace this or even clean it. i tried taking it off but it seems like there is a curved tube in the engine block that does not allow me to take it off.
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Old Mar 4, 2005 | 01:58 PM
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From: Southern Calif
96 e320
I'd like to know how to take this metal tube off too. I just got that p0400 reading.
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Old Mar 4, 2005 | 05:15 PM
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I also would appreciate a DIY (with photos) as to how to clean metal tube on EGR valve to remedy the P0400 fault. This is more than annoying!
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Old Mar 17, 2005 | 09:36 PM
  #12  
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From: Fort Lauderdale , Florida
2003 e320
Originally Posted by EdS320
Solved the problem after removing the EGR which was fine and not blocked. Also Air Pump whine post...After changing the oil I wiped some grease from an electrical connector at the front of the engine, behind the wiring was plastic vacuum tubing that supplies vacuum to the EGR and Secondary Air Pump nest to the EGR Valve by way of the electric solenoids vacuum valves at the front left of the engine. I had inadvertently broken the BRITTLE vacuum tubing, thus killing the vacuum to the solenoids. I put in a rubber vacuum tube splice to reconnect the line ends.

*CAREFUL when you work with or around the tan colored vacuum tubing, as it ages it gets VERY BRITTLE and will break at the slightest bend or pressure. The same tubing runs next to the spark plugs and coils under the engine top cover. If it does break on you, you can use small diameter rubber tubing to reconnect the broken ends together.

I also found the vacuum tubing had cracked and replaced it the way you suggested. How do I reset the trouble light to see if it stays off?
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Old Apr 13, 2006 | 03:35 PM
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1998 ML 320 with same P0400

Went to my Benz tech in west L.A. who diagnosed the problem with the result of a P0400 error code. He stated the problem might be a bad gasoline cap. Is he right. He said the next step is to buy a new gas cap and then do a recheck to see if this fixes the problem. Any info will be greatly appreciated.
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