View Poll Results: Hi
Hi
0
0%
Hi
0
0%
Voters: 0. You may not vote on this poll
W204 - P0720 and P0721: car doesn’t move but engine runs smoothly
Thread Starter
Newbie
Joined: May 2023
Posts: 4
Likes: 0
2013 c300
W204 - P0720 and P0721: car doesn’t move but engine runs smoothly
Hi all,I have a 2013 C300 sport package. I have recently got error codes P0720 and P0721, and my car doesn’t move anymore. Despite the engine starting and running smoothly, the car refuses to move when I shift into drive, and the RPMs rise when I press on the gas pedal. On two occasions, the car randomly began to function again, and I was able to drive it for approximately 50km before it failed once more. Before coming to a complete stop, the RPMs goes up a lot to just reach a speed of 20km/h.
I am wondering if anyone else has encountered this issue and if they have any ideas about what may be wrong with my car. Thank you.
I am wondering if anyone else has encountered this issue and if they have any ideas about what may be wrong with my car. Thank you.
Last edited by Vibi; May 13, 2023 at 11:16 PM.
MBWorld Fanatic!
Joined: Sep 2013
Posts: 2,346
Likes: 692
2021 GLB250 FWD, 2023 GLA250 FWD, 2013 C250, 2015 GLK350, 2005 ML350SE, 2003 E320
Hi all,I have a 2013 C300 sport package. I have recently got error codes P0720 and P0721, and my car doesn’t move anymore. Despite the engine starting and running smoothly, the car refuses to move when I shift into drive, and the RPMs rise when I press on the gas pedal. On two occasions, the car randomly began to function again, and I was able to drive it for approximately 50km before it failed once more. Before coming to a complete stop, the RPMs goes up a lot to just reach a speed of 20km/h.
Thread Starter
Newbie
Joined: May 2023
Posts: 4
Likes: 0
2013 c300
These codes inducate that the ECM is not getting useable information from the transmission. Indications are that P0721 is from a failed output speed sensor on the conductor plate. However, since P0720 is also present, a check that the wiring harness connector is not oil wetted and has continuity is in order. These codes usually result in the transmission going into limp mode (2nd gear only) but not complete failure to move. Since the car will not move at all, failure of solenoids or the valve body may also be involved. If you have a scanner and not just a code reader, viewing real time transmission data may allow a more precise diagnosis.
MBWorld Fanatic!
Joined: Sep 2013
Posts: 2,346
Likes: 692
2021 GLB250 FWD, 2023 GLA250 FWD, 2013 C250, 2015 GLK350, 2005 ML350SE, 2003 E320
Many if the members have various iCarsoft scanners. Maybe one of them can comment. I’m not familiar enough to recommend. I have an 8 year old Autel that works fine for me. It was at the lower end of their models and I don’t have the add on attachments. When deciding, do get one that can be upgraded online by downloading.
Newbie
Joined: May 2023
Posts: 13
Likes: 8
2008 c300 manual, 2012 c300 4matic, 2008 r320, 2012 c250 3.5l swapped, glc 63
Car is in gear, but you get zero movement. That sounds like no fluid circulation and no clutch engagement. My guess is the ears that drive the pump via the torque converter snapped. If you clear codes and get no hard faults from transmission, it’s hard parts that are broken.
Trending Topics
Thread Starter
Newbie
Joined: May 2023
Posts: 4
Likes: 0
2013 c300
Car is in gear, but you get zero movement. That sounds like no fluid circulation and no clutch engagement. My guess is the ears that drive the pump via the torque converter snapped. If you clear codes and get no hard faults from transmission, it’s hard parts that are broken.
MB World Stories
The Best of Mercedes & AMG
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
10 Most Reliable Mercedes-Benz Models You Can Buy Used
Verdad Gallardo
Newbie
Joined: May 2023
Posts: 13
Likes: 8
2008 c300 manual, 2012 c300 4matic, 2008 r320, 2012 c250 3.5l swapped, glc 63
If you can see live data, you will see input shaft reading rpm and output shaft at 0. That is a confirmation that there is no fluid circulating in the transmission. If it was a conductor plate you would get a bunch of other codes and you’d be in limp mode but still able to drive.
MBWorld Fanatic!
Joined: Sep 2013
Posts: 2,346
Likes: 692
2021 GLB250 FWD, 2023 GLA250 FWD, 2013 C250, 2015 GLK350, 2005 ML350SE, 2003 E320
If you can see live data, you will see input shaft reading rpm and output shaft at 0. That is a confirmation that there is no fluid circulating in the transmission. If it was a conductor plate you would get a bunch of other codes and you’d be in limp mode but still able to drive.
Newbie
Joined: May 2023
Posts: 13
Likes: 8
2008 c300 manual, 2012 c300 4matic, 2008 r320, 2012 c250 3.5l swapped, glc 63
Yes I’m an mb tech, this is not a common failure. I’ve seen this happen 2 times in the last 8 years. 2nd time was my fathers car. It’s a fluke failure.
Newbie
Joined: Jul 2024
Posts: 1
Likes: 0
W204 09 C300 4matic sport
I just had the exact same issue
Hi all,I have a 2013 C300 sport package. I have recently got error codes P0720 and P0721, and my car doesn’t move anymore. Despite the engine starting and running smoothly, the car refuses to move when I shift into drive, and the RPMs rise when I press on the gas pedal. On two occasions, the car randomly began to function again, and I was able to drive it for approximately 50km before it failed once more. Before coming to a complete stop, the RPMs goes up a lot to just reach a speed of 20km/h.
I am wondering if anyone else has encountered this issue and if they have any ideas about what may be wrong with my car. Thank you.
I am wondering if anyone else has encountered this issue and if they have any ideas about what may be wrong with my car. Thank you.
Hey!
I hope this finds you well. Did you ever get that issue fixed? What was the issue? When I read your post it's like you were sitting in the car with me. Haha
I got the same cods. Found it may be the catalytic converter. Now if it would need to be welded or replace the whole pipe.
Lmk thank you
