I had a maf code so I a new maf in and now having instant p0400 codepopping up. P0243 also pops up but not as much. Ii swapped transduders and no change. Is there any ways to test the vaccume points. What would trigger these 2 codes at the same time?

__________________
1993 e300
1995 e320
1994 e320
2006 s500 4matic
2004 Jeep wj overland
2001 Ducati 748
2004 Honda shadow aero

Well...

P0400 is MAF sensor. Did you get a new Bosch MAF or a 3rd party model? I've heard of people having issues with non genuine Bosch MAFs.

P0243 is Wastegate Actuator Solenoid A Malfunction.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Oh..thought p0100 was maf. P0400 is coming up as egr flow malfunction in my scanner.

__________________
1993 e300
1995 e320
1994 e320
2006 s500 4matic
2004 Jeep wj overland
2001 Ducati 748
2004 Honda shadow aero

Yes you're right P0100 is MAF and P0400 is EGR. When my MAF failed I was getting both codes so I had them confused.

But when I replaced the MAF it made both codes go away.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Mine used to trip PO243 everytime I went up Andrade grade on Hwy 680. Was never able to resolve it. PM me your email and I'll send you the test procedures. Can be electrical and/or vacuum isues with the tranducers. I never had much luck swapping them, pretty sure boost and egr codes set at very different values with boost being more particular.

The solution for me was backing off the go pedal going up that hill after 5 secs for a split second and then feeding it more power again. The code sets at 6 secs. Easy to avoid when you understand that.

__________________
Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

When the vehicle reaches a steady cruise around 60 MPH with a steady throttle position, the ECU opens the waste gate to reduce the back pressure and increase economy. P0243 happens sometimes when the ECU is trying to reduce boost and boost remains high for whatever reason.

__________________
-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

The maf I bought is a bosche part ..I got it from pelican but it was the cheaper of the 3 options I had. Only had a 0100 code till I changed the maf then came the other 2 codes.

Does anyone have a diagram as to where the lines go for both transducers? Maybe I got them hooked up wrong

__________________
1993 e300
1995 e320
1994 e320
2006 s500 4matic
2004 Jeep wj overland
2001 Ducati 748
2004 Honda shadow aero

Ok so I think I might have found my 0243 problem. The vac line was severed..but still doesn't seem to have vac. The nipple labled atm goes to the vent?

__________________
1993 e300
1995 e320
1994 e320
2006 s500 4matic
2004 Jeep wj overland
2001 Ducati 748
2004 Honda shadow aero

Yes on a vacuum transducer, the ATM port (ATMosphere) is the vent.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Is there a way to check the egr function without taking the intake off?

__________________
1993 e300
1995 e320
1994 e320
2006 s500 4matic
2004 Jeep wj overland
2001 Ducati 748
2004 Honda shadow aero

OK SO i found the problem. A mouse got inside the car and chewed through the vac line. I taped up the line and all is solved.

__________________
1993 e300
1995 e320
1994 e320
2006 s500 4matic
2004 Jeep wj overland
2001 Ducati 748
2004 Honda shadow aero

The mice love that space under the wiper assembly between the 2 firewall sections...

__________________
-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

Hey Evan!

This thread is particularly interesting.

Your post about the ECU dropping boost for economy on the highway has got me thinking.

I have been running a pressure waste gate on my 99 for years. I only seem to get a P0243 code on the highway more so in the winter time.

Is there an electrical schematic I can introduce similar to your EGR/MAF mods?

Your help is always GREATLY appreciated!

__________________
-disav

99 E300 TURBODIESEL Astral Silver 282K - AMG brakes, suspension, monoblocks, speedo & interior - Full Load Maxed on IP by custom Speed Tuning USA Chip - T3/T4 Garrett - EGR/MAF delete
98 E300 TURBODIESEL Alexandrite Green on black leather 289K
95 E300 DIESEL Green Queen 267K SOLD
84 300D 216k SOLD
87 300D 299K #22 head - intercooler - full load adj. - 8sec 0-60mph - SOLD
76 300D 214K SOLD

I am currently battling the same issue(s) with our 1999 E300. Replaced MAF, now get P0400 codes. Anyone have any diagram(s) of the vacuum lines controlling the EGR? I have the top of the EGR valve nipple capped off. Curious where it goes to.

The EGR line is simple, it runs from the EGR modulator to the EGR "mixing chamber" in the intake. The other end runs down to a "Y" in the vacuum lines under/near the brake vacuum booster.

__________________
-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250