Mercedes-Benz Forum banner

1 - 5 of 5 Posts

·
Registered
Joined
·
14 Posts
Discussion Starter #1
took my car for a short ride and noticed it was acting weird
stuck in limp mode
got back home and checked for codes and got P0720
and after some reading on here and other places got
output speed sensor circuit malfunction

somehow the car got out of limp mode but i still wanna do something about the problem

any idea on where the problem is , specifically where is the sensor or part that i would need to replace and would it be a relatively simple DIY job , ill have help from someone who is somewhat knowledgeable about cars, or would it be best if i took it to dealer
 

·
Registered
1998 c230 170K
Joined
·
1,415 Posts
Got brake dust?

took my car for a short ride and noticed it was acting weird
stuck in limp mode
got back home and checked for codes and got P0720
and after some reading on here and other places got
output speed sensor circuit malfunction

somehow the car got out of limp mode but i still wanna do something about the problem

any idea on where the problem is , specifically where is the sensor or part that i would need to replace and would it be a relatively simple DIY job , ill have help from someone who is somewhat knowledgeable about cars, or would it be best if i took it to dealer
Yes, we all enjoy intermittant problems:p Sounds like there may be a build up of brake dust on one or all the ABS sensors, you might want to pull off the wheels and give a good cleaning of the brake hardware. There may be some caking of dust and dirt on the sensors. Hopefully this will save you from going to the (you know who). and it won't cost you much other than some quality time with your favorite vehicle:) B
 

·
Registered
'99 2.3L Kompressor
Joined
·
1,944 Posts
Unfortunately, I believe this code refers to a problem with the transmission. Do some searching for speed sensor and transmission across the various model forums here. This problem has cropped up before. I am not sure that the cure is DIY for most people, but if I remember correctly, it at least is something that can be cured without requiring a full tranny removal and disassembly.
 

·
Registered
Joined
·
14 Posts
Discussion Starter #4
thanks for your responses

the brake dust makes sense and would explain how it cleared up the next day
gonna wait till the morning and check up on it and do some more reading on the sensors :thumbsup:
 

·
Registered
Joined
·
175 Posts
Unfortunately, I believe this code refers to a problem with the transmission. Do some searching for speed sensor and transmission across the various model forums here. This problem has cropped up before. I am not sure that the cure is DIY for most people, but if I remember correctly, it at least is something that can be cured without requiring a full tranny removal and disassembly.
+1

The OP's Diagnostic Trouble Code is P0720:

P = this code is thrown due to a fault detected in the powertrain system.
0 = is generic as oppose to manufacturer specific (1).
7 = means it is coming from the "transmission controls" subsystem.

How would ABS speed sensors come into play for this code? It would not make sense to me for the engineers to use wheel speeds for the transmission controls requirements. They would have used some sensor to give much more direct readings. For rear wheel drive, the front wheels are not locked-stepped to the transmission output shaft (no direct connection), and the rear wheels can have varying speeds due to the rear differential actions (ie. when turning a corner, or while slipping).
 
1 - 5 of 5 Posts
Top