2008 cls 550 secondary air PO140 code
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Junior Member
Joined: Dec 2015
Posts: 26
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From: Naples Florida
2008 cls550 2007slk280
2008 cls 550 secondary air PO140 code
Please help, my 2008 cls 550, PO140 code keeps coming back on. The pump works and sounds normal. I also replaced the relay and the little air vacuum part and PO140 keeps coming on. This is usually what happens, I start the car cold and the RPM's goes to 1,100. After 8 to 10 seconds the RPM's drop to 900 RPM's. Then after about 5 seconds the idle drops to about 675 RPM's. Shortly after , maybe after about 10 seconds the Check Engine light comes. Does anybody have a idea how to solve the problem? Also if someone could show me the proper location in the fuse box. I know it is on the firewall and is located on the driver side. I would also like to know the part number for this relay. Thank you for all your help. Bob Kohl
P.S. I am looking for a Mercedes Mechanic who does side work and is reasonable. I live in Naples Florida. Thank you
P.S. I am looking for a Mercedes Mechanic who does side work and is reasonable. I live in Naples Florida. Thank you
Out Of Control!!
Joined: Jul 2003
Posts: 15,901
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From: North Scottsdale, AZ
'71 Pinto
Replace oxygen sensor part # 0045420718 explained here: http://www.mercedesmedic.com/how-to-...mercedes-benz/
$60.78/free shipping https://www.amazon.com/gp/product/B0...SIN=B000CF1XCM
$60.78/free shipping https://www.amazon.com/gp/product/B0...SIN=B000CF1XCM
Thread Starter
Junior Member
Joined: Dec 2015
Posts: 26
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From: Naples Florida
2008 cls550 2007slk280
Same old problem
Hello Dan,
This is Bob Kohl with the 02sensor problem. I replaced that sensor as you suggested and the PO1040 code comes up again. I don't get it. When I start the car cold, it goes to 1100 rpm. After about 10 seconds it drops to 975 rpm and the engine starts to runs rough. Then after about 8-10 seconds the idle drops to 675 and continues to run rough. After another 10 seconds the check engine comes on, now I am baffled. Do you have any more ideas?
Thanks Dan,
Bob Kohl
This is Bob Kohl with the 02sensor problem. I replaced that sensor as you suggested and the PO1040 code comes up again. I don't get it. When I start the car cold, it goes to 1100 rpm. After about 10 seconds it drops to 975 rpm and the engine starts to runs rough. Then after about 8-10 seconds the idle drops to 675 and continues to run rough. After another 10 seconds the check engine comes on, now I am baffled. Do you have any more ideas?
Thanks Dan,
Bob Kohl
Out Of Control!!
Joined: Jul 2003
Posts: 15,901
Likes: 4,632
From: North Scottsdale, AZ
'71 Pinto
P0140 should be bank 1, sensor 2 = passenger side downstream/behind CAT. If correct sensor was installed properly (most common culprit), and you cleared code check for inappropriate fuel pressure, faulty fuel injectors, intake air leaks, and/or exhaust gas leakage.
Thread Starter
Junior Member
Joined: Dec 2015
Posts: 26
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From: Naples Florida
2008 cls550 2007slk280
Dan,
Thanks again for your quick response. I guess the only way to check all that you have mentioned is to take it to MB of Naples and have them do a diagnostic check. I really hate going there but I guess I have no other choice. Thanks again for all your help, I really appreciate it. I will let you know if I get it figured out.
Bob
Thanks again for your quick response. I guess the only way to check all that you have mentioned is to take it to MB of Naples and have them do a diagnostic check. I really hate going there but I guess I have no other choice. Thanks again for all your help, I really appreciate it. I will let you know if I get it figured out.
Bob
