How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Marty Your Own Question
Marty
Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 53777
Experience:  Bosch Certified Master Tech. Over 35 years experience.
13230946
Type Your Mercedes Question Here...
Marty is online now
A new question is answered every 9 seconds

S430: the gearbox is sticking in limp home mode every so often..clears

Resolved Question:

I have a 2001 w220 S430, the gearbox is sticking in limp home mode every so often. If I shut the car down and restrat it clears.
Submitted: 7 years ago.
Category: Mercedes
Expert:  Marty replied 7 years ago.
Hi Steve, do you have any warning lights lit?

Marty
Customer: replied 7 years ago.
no, nothing. It started about 6 months ago, I did a 1200 mile run at at the end of teh run it did it once. It then was ok for a month and no is starting to get more regular.
Expert:  Marty replied 7 years ago.
Ok, first you should have the fluid level checked and then have the car connected to the Mercedes diagnostic tester and do a complete scan of all of the systems. There are going to be fault codes stored in either the engine, transmission or brake control units. There are quite a few possibilities. Most often we see fluid contamination into the 13 pin electrical connector at the front of the transmission. You can have the connector visually inspected first. We also see faults with the electric plate inside the transmission but the connector problem might tend to be more erratic like you are experiencing. There are other possibilities for limp home and the fault codes will be the clue. Let me know if you have any questions.

Marty
Customer: replied 7 years ago.
Is it likely to be a big problem, I live in the UK but the car is in Spain at my 2nd house and I dont have gargaes here that I know. Am I best to sell the car quickly rather than face a big garage bill??
Expert:  Marty replied 7 years ago.
How many miles are on the car?
Customer: replied 7 years ago.
76000 miles.

Can I check this connector myself. The fluid I cant check as it appears to need a special mercedes tool to check it.
Expert:  Marty replied 7 years ago.
The connector is underneath the car at the right front of the transmission. It's a little difficult to get to unless you can safely lift the car. you'll need to rotate the outer lock ring counterclockwise to release the harness. 76,000 miles isn't a lot of miles for that transmission. I wouldn't be in a hurry to get rid of the car, I'd at least have it scanned first. You can order a dipstick from Mercedes for $39.00 or you can make a crude one out of a lawnmower choke cable housing or the like. You'll need to mark the housing at 65 mm from the bottom. That will be the full level when hot. Insert the cable all they way into the tube until it bottoms out.
Customer: replied 7 years ago.
ok thanks, XXXXX XXXXX get any fault codes any other way through the car rather than taking it to a garage??
Expert:  Marty replied 7 years ago.
No, the diagnostic tool is required and it must be able to read all of the systems, engine, transmission and braking.
Customer: replied 7 years ago.
Will it only be mercedes garages that have these machines??
Expert:  Marty replied 7 years ago.
For the most part I think yes. You should call and ask if the shop has the software for the Mercedes. Everyone can read engine codes but the other systems really need the Mercedes factory level tool.
Customer: replied 7 years ago.
ok thanks, XXXXX XXXXX when I cjeck the ATF do I need the engine running or hot??
Expert:  Marty replied 7 years ago.
No problem Steve, you need to have the engine running at operating temperature (80°C). Take it for a little ride and then come back and check it with the car on level ground.
Marty and 3 other Mercedes Specialists are ready to help you
Customer: replied 7 years ago.
ok thanks
Expert:  Marty replied 7 years ago.
You're welcome Steve :-)
Customer: replied 7 years ago.
I took the car in to a service centre today and they put it on their SUN system. They said they reprogrammed all the ecu's and it all seems ok again now. It may have been jump started by the car park people at the airport last week as it gets left there for a month at a time. Could this be the issue??

If it happened again is there any way I could od the repair myself??

Thanks
Steve
Expert:  Marty replied 7 years ago.
I think all the shop did is erased all of the fault codes. It may very well happen again. If it does I'd like you to have them give you a printout of the codes before they erase them. It's probably not going to be a repair you can do yourself.
Customer: replied 7 years ago.
ok, thanks. Does it seem that it could be more electronic than mechanical??
Expert:  Marty replied 7 years ago.
At the moment it does. Most of the problems we see are electronic in nature.
Customer: replied 7 years ago.
The car played up again so i took it back to the garage. I am struggling to communicate with them as I am in Spain, they reset the computer and told me it is speed sensor 3 that is showing us as faulty on the fault codes. They didnt give me any more information than this. Does this make any sense??
Expert:  Marty replied 7 years ago.
It sounds like a bad 13 pin connector or electrics plate Steve. Are they familiar with the common problems of this transmission?
Customer: replied 7 years ago.
They appear to have no idea, they plug in the computer and reset it so it works for a bit and then stops again. Maybe I'll try the 13 pin connector, its under the car isnt it??
Expert:  Marty replied 7 years ago.
Yes the connector is at the right front of the transmission where the harness connects. Have them undo the harness and inspect for fluid contamination.
Customer: replied 7 years ago.
I think I'll have a look myself. is it underneather the car or on top of the transmission??
Expert:  Marty replied 7 years ago.
It's underneath at the right front corner just above the pan. Rotate the outer ring of the connector counterclockwise and pull it off.
Customer: replied 7 years ago.
OK, I see its nots omething I can get to without ramps etc so i'll have to wait until next time im here and find another more useful garage. Thanks for your help
Expert:  Marty replied 7 years ago.
You're welcome Steve.