Hi, I have a Mercedes Benz c320 4matic 2005. I have some problems with it.
First it popped up the ABS light, and I drove like a week with that. Now it’s showing transmission problems. It is not changing gears, sometime it does but sometime you are stuck with the same gear all the way up, and then the check engine light comes on. Also when I put it in D, sometimes it makes a hard harsh noise (clunk)like the transmission hitting something and if that happens I know that it’s not going to change gears. What can it be?
the ABS light is relates to a speed sensor.
can you help me? Thank you!

 

First, get a scanner like this and scan for codes. Then come back and tell us what you found. I assume you have the 7-speed 7G-tronic, or is yours the 5-speed?

 

Transmission issues could be from low fluid, which may trigger the check engine light also. I'm not sure if your car has the transmission fluid dipstick or not, check with the photo below.

As stated above a Mercedes specific scanner would be helpful for figuring out the abs light. Point you in the right direction which one it is if its a wheel speed sensor.

 

The 2005 C320 is a W203, so post this question there also. This is the W204 Forum.

Speaking for the OP here, but the 2005 C320 should have a 5 speed 722.6 5G-Tronic transmission behind a 3.2 L W112 engine.

I think @TimC300 has the photo correct. 722.6 transmission will not have a dipstick, but will have a fill tube with a removable cap that can be used with an aftermarket dipstick to check the fluid level.

 

Hi, I did a scan and it’s showing this:




These as secondary, that makes me think that the ABS light could make these problems show.

These are a lot of codes right?

 

Yeah, my car has a 5 speed automatic transmission.
And correct it needs a dipstick to check it.

 

Who did the scan and what scanner did they use? At least one of the codes is WRONG. That is why I said to get the scanner I provided a link to. Do not use a generic scanner on a Mercedes.

 

More diagnostics need to be done. You may need a new conductor plate. The good news is that on your transmission, it's relatively inexpensive as compared to the 7G transmissions.

When was the transmission fluid last changed?

 

[QUOTE=JettaRed;8917769]

I bought the car 4 months ago, and it was working fine. But I don’t know when was the fluid last changed, and I haven’t changed the transmission fluid because I want to know if the damage is to big and very expensive I wouldn’t invest money in the car, like if the transmission it’s gone.
I did the scan at AutoZone, I think they use an OBD2 scanner.
Do you think that the ABS/speed sensor not working would be relates to the gears not shifting considering that they can’t understand the speed of the wheels?

 

If you turn the car off and back on, are the symptoms still present or do they take a little while to return?

If it was ABS only, I'd say it might be the wheel speed sensors and/or tone ring. But if the tranny is clunking just from putting it in gear, it's probably the transmission. You are also driving a 19 year old car (time for historic car plates next year). If the tranny fluid has never been changed, that's a problem. I don't know the frequency to change the tranny fluid for your car, but you should look it up. You could try replacing the wheel sensors, which should be done anyway, but I think someone needs to diagnose the transmission. You can always ask Mercedes to check the history of the car and see if a transmission service was ever performed.

 

Yeah it’s an old car, but it has only 122k miles, and I think it should last a little longer, but you never know how the owner before took care of it.
It should be changed every 50k miles. Like right now I’m looking for a simpler solution than taking it to the Mercedes, because everything costs now.
Should perform a fluid change asap, and change the speed sensor, and clean or replace the multipole ring(magnetic).
I wonder if anyone had these issues, like what can it be for the transmission to make that hard noise that much that makes the car shake when you put it in D or R.
The ABS light it’s on all the time, sometimes the check engine comes on. When I turn it on, in the beginning it changes the gear for a short time, but sometimes it doesn’t shift gears at all from the beginning and I’m stuck with 20mph.

 

If it were me I would buy a transmission fluid dipstick and check the fluid level. Can buy one tonight off Amazon for $10 and have it delivered tomorrow. Check the fluid level according to your owners manual. You can see if the fluid is low and check the condition of the fluid at the same time. If the level is low add some, drive around and see if anything changes.

I would not rely on the Autozone obd scanner. I searched around online for "Mercedes P2402" and came across a few different explanations than you posted above. P2402 could apply to the front right wheel speed sensor. Here is a cut and paste I found in a Mercedes forum from someone who used a Mercedes scanner as an example:



Either use a Mercedes specific scanner, or go to a Mercedes dealer and have them scan the car and give you the results.

 

What is your source of information about how often the tranny fluid should be changed? The first generation of the 7G transmission is every 39,000 miles. The later generations (FE) every 77,500 (or five years).

Regardless, if you find the fluid is low after checking like @TimC300 said and top it off, I would get a fluid change as soon as possible. It's not hard to do it yourself, especially with your transmission.

 

[QUOTE=Truecars;8917785]Okay. Here we go. Hang on for the ride.

The 722.6 transmission does not have an output speed sensor. So where does the the P0720 code come from? Well, your question about the ABS failure being related is a very good speculation. The ECM must have an output speed input to perform its shift calculations. So it uses the rear wheel speed sensors as a proxy.

Therefore, before you can even begin to diagnose your transmission, you need to get all of your ABS issues resolved. I suggest that you get a dedicated MB scanner for your new toy and double check all these things before you begin. Then start with the rear wheels and get the ABS working properly.

Next, rescan the car, looking specifically at transmission codes, which you won’t get with a generic scanner. A multi vehicle scanner that has a dedicated MB program is fine. You might find that the transmission is healthy. But go ahead a change the fluid and filter as who knows when/if it was done. If you don’t have the shop to do it yourself, find a German car shop that has a Mercedes specialist. They can get you back on the road for a lot less than a dealer.

A W203 C320 is a really nice car when it’s right.

 

[QUOTE=Odd Piggy;8917936]Hi guys. Gotta thank you for your opinions thank you very much. I scanned the car with a specific Mercedes Benz program, and I got these codes.
I got trouble codes on the engine, transmission and ESP and some other little things, but when I erased them, all of them went away, they cleared except the EPS codes(So I think I should focus on the ABS speed sensor first and the magnetic on rear right wheel. These are the codes.

 

Hi! I’m just mentioning you again to see what you think about the codes I got from scanning. I uploaded the codes earlier.