2002 ML500 Check engine light on
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Newbie
Joined: Nov 2018
Posts: 1
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From: Los Angeles
ML500
2002 ML500 Check engine light on
Hi there,
I am relatively new to the forum and have decided to try and maintain my truck on my own instead of spending 300-500 every time I go to the mechanic. My ML500 has 380k miles on it, still runs like a dream, but had the check engine light come on and plugged in the Micro Mechanic in to read what was going on. I am getting the code P0171, P0104, P0422, P0432, and P0404. Also, when I opened the hood it seems that the coolant is bubbling at the connecting point and seems a bit low. Any and all help would be greatly appreciated! Thanks!
I am relatively new to the forum and have decided to try and maintain my truck on my own instead of spending 300-500 every time I go to the mechanic. My ML500 has 380k miles on it, still runs like a dream, but had the check engine light come on and plugged in the Micro Mechanic in to read what was going on. I am getting the code P0171, P0104, P0422, P0432, and P0404. Also, when I opened the hood it seems that the coolant is bubbling at the connecting point and seems a bit low. Any and all help would be greatly appreciated! Thanks!
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Joined: Nov 2015
Posts: 1,456
Likes: 140
From: Westcoast/Interior
02w163ML500 / 97w210E50AMG / 99w202C230k / 95w124500e-wip
P0171 System too Lean (Bank 1) ) faulty air mass flow sensor
P0104 Mass or Volume Air Flow Circuit Intermittent
P0422 (main catalyst efficency below threshold bank 1)
P0432 (main catalyst efficency below threshold bank 2)
P0404 EGR issue - Faulty EGR valve / Faulty EGR sensor/ EGR sensor wiring/connector problems / Carbon buildup in EGR valve
For the first 2, could be the MAF. disconnect the MAF for a drive and see if it changes anything. It sets ECU to default setting.
The 2nd two relate to Oxygen sensors - they may be going.
Last one, EGR probably needs to either be replaced or cleaned out.
As to the bubbling coolant, what connection point are you referring to? More info?
Have you got a small leak somewhere. maybe long the edges of the rad?
Inspect the garage floor just below the rad area for signs of a leak. (put down some corrugated cardboard)
P0104 Mass or Volume Air Flow Circuit Intermittent
P0422 (main catalyst efficency below threshold bank 1)
P0432 (main catalyst efficency below threshold bank 2)
P0404 EGR issue - Faulty EGR valve / Faulty EGR sensor/ EGR sensor wiring/connector problems / Carbon buildup in EGR valve
For the first 2, could be the MAF. disconnect the MAF for a drive and see if it changes anything. It sets ECU to default setting.
The 2nd two relate to Oxygen sensors - they may be going.
Last one, EGR probably needs to either be replaced or cleaned out.
As to the bubbling coolant, what connection point are you referring to? More info?
Have you got a small leak somewhere. maybe long the edges of the rad?
Inspect the garage floor just below the rad area for signs of a leak. (put down some corrugated cardboard)
MBWorld Fanatic!
Joined: Oct 2011
Posts: 7,107
Likes: 765
From: Bronx, N.Y.
2002 ML 320 & 2006 ML500
Bubbling coolant could be defective coolant cap, defective thermostat, or head gasket which probably explains the bubbling and low coolant level.
Block Tester is the best.
Block Tester is the best.
Last edited by Maj. Dundee; Dec 10, 2018 at 03:05 AM.
