Mercedes-Benz Forum banner
1 - 18 of 18 Posts

Registered
2005 ML 500, 2002 ML 320, 1998 ML320
Joined
51 Posts
Discussion Starter · #1 ·
We have had our 2005 ML 500 for just over a year and it has 77,000 miles. About 6 months ago it developed a thumping noise at idle coming from the intake. It disappears as soon as the engine revs above idle. There are several threads in this forum that describe the problem with flaps inside the intake. Until recently, it ran fine and did not have any hesitation. This past week, it started stalling occasionally when the hesitation occurs. This happens only after coming to a complete stop. I ran a scan and this code, P2071-8, showed up. I have run periodic scans in the past and this code has not shown up before. Since it ran fine for months, I am not sure the the intake issue is causing the hesitation. I cleaned the MAF sensor as I read that could cause an issue. I am asking for some direction to help diagnose and fix the hesitation and stall issue. Thanks
 

W163 and General M Gremlin
Joined
7,724 Posts

Registered
Dallas, Texas
Joined
9,759 Posts
We have had our 2005 ML 500 for just over a year and it has 77,000 miles. About 6 months ago it developed a thumping noise at idle coming from the intake. It disappears as soon as the engine revs above idle. There are several threads in this forum that describe the problem with flaps inside the intake. Until recently, it ran fine and did not have any hesitation. This past week, it started stalling occasionally when the hesitation occurs. This happens only after coming to a complete stop. I ran a scan and this code, P2071-8, showed up. I have run periodic scans in the past and this code has not shown up before. Since it ran fine for months, I am not sure the the intake issue is causing the hesitation. I cleaned the MAF sensor as I read that could cause an issue. I am asking for some direction to help diagnose and fix the hesitation and stall issue. Thanks
That fault has nothing to do with engine running. Most likely caused by low voltage at startup. Any faults in other modules?

Here is scan from my ML350.
 

Attachments

Registered
2005 ML 500, 2002 ML 320, 1998 ML320
Joined
51 Posts
Discussion Starter · #6 ·
Witek_M:
C1210 - Terminal 30 undervoltage
C1181 - N49 Steering angle sensor fault
C1350 - B24/15 Rotary speed and lateral acceleration sensor not initialized
C1035 - Signal from N49 faulty
C1174 - N49 steering angle sensor not initialized

B1981 - CAN bus N41 fault in communication (trip computer does not work)

4 codes related to windows and mirrors (all work perfectly)

All these codes have been present since I purchased the vehicle.
 

Registered
Dallas, Texas
Joined
9,759 Posts
Witek_M:
C1210 - Terminal 30 undervoltage
C1181 - N49 Steering angle sensor fault
C1350 - B24/15 Rotary speed and lateral acceleration sensor not initialized
C1035 - Signal from N49 faulty
C1174 - N49 steering angle sensor not initialized

B1981 - CAN bus N41 fault in communication (trip computer does not work)

4 codes related to windows and mirrors (all work perfectly)

All these codes have been present since I purchased the vehicle.
And they will not clear? Or they clear and come right back?
 

Registered
2005 ML 500, 2002 ML 320, 1998 ML320
Joined
51 Posts
Discussion Starter · #8 ·
They all come right back. Would those faults affect engine?

This happens to be my wife's car and she reported the hesitation about 2 weeks ago. I was with her when is stalled this past weekend and there was a noticeable hesitation. I took it out last night for over an hour and probably did 200 stop/starts from all different speeds (in a large, empty parking lot) and it did not present any hesitation. I had my scanner providing live data and the RPMs did not drop at all. MAF sensor was cleaned a few days ago per my initial post. Wondering if I should be looking at fuel system or vacuum leak.
 

W163 and General M Gremlin
Joined
7,724 Posts
Wouldn't hurt you to perform a vacuum test on these old beasts and fpressure test.
When was the fp last changed?
 

Registered
2005 ML 500, 2002 ML 320, 1998 ML320
Joined
51 Posts
Discussion Starter · #10 ·
I am assuming it is original with 77,000 miles. Any idea what the pressure should be?
 

W163 and General M Gremlin
Joined
7,724 Posts
I am assuming it is original with 77,000 miles. Any idea what the pressure should be?
55-65psi
36psi at rest, after 30mins.
 

Registered
2004 SL600; 2004 SL500;1996 SL600;2003 ML350; 1997 C280 Sport; 1987 190e 2.3 16v; 1986 190e 2.3 16V;
Joined
776 Posts
FWIW I 've had quite a few Benzes. At least three of them had similar symptoms, and I never got a code for any of them. It was the EGR valve in all three.
 

Registered
Dallas, Texas
Joined
9,759 Posts
FWIW I 've had quite a few Benzes. At least three of them had similar symptoms, and I never got a code for any of them. It was the EGR valve in all three.
Good point. Lazy closing EGR valve may cause rough running and stall coming to a stop.
Easy to evaluate. Disconnect and plug vacuum line to EGR valve. It will trigger P0400 fault.
 
  • Like
Reactions: ml foot

Registered
Dallas, Texas
Joined
9,759 Posts
They all come right back. Would those faults affect engine?
You need to look at battery voltage. Have battery tested or get your own tester.

 
  • Like
Reactions: ml foot

Registered
2002 ml55
Joined
644 Posts
You need to look at battery voltage. Have battery tested or get your own tester.

I was going to add this note... check to make sure battery and/or alternator are in good working condition..... when idling you can simply attach a volt meter to your battery and see what is being produced through the system ... (I believe minimum should be 13.5... but dont quote me... but somewhere bet 13.5 - 14.3 is the sweet spot).....

also... go to local pep boys / auto zone etc... they can do a test on the battery - that will also test the alternator... should cost anywhere from $free - $15.
 

W163 and General M Gremlin
Joined
7,724 Posts
I was going to add this note... check to make sure battery and/or alternator are in good working condition..... when idling you can simply attach a volt meter to your battery and see what is being produced through the system ... (I believe minimum should be 13.5... but dont quote me... but somewhere bet 13.5 - 14.3 is the sweet spot).....

also... go to local pep boys / auto zone etc... they can do a test on the battery - that will also test the alternator... should cost anywhere from $free - $15.
sidebar....
:)
You made it. 馃嵒
Screen Shot 2021-07-23 at 5.32.42 PM.png
 

Registered
2005 ML 500, 2002 ML 320, 1998 ML320
Joined
51 Posts
Discussion Starter · #18 ·
Thank you for all the tips. Unfortunately work has been a bit crazy this past week and this was my weekend to work. Plan is to test fuel pump, EGR and battery this week and report back..
 
1 - 18 of 18 Posts
Top