Auto gearbox problem, gears won't engage and all feel like neutral

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DIXYY

New Member
Joined
Oct 21, 2022
Messages
4
Location
Scotland
Car
C215
Hi, I have a problem with my C215 CL55K AMG gearbox.

Last week I was stopped at a red light, I went to put the car into neutral, but the shifter was stuck in drive, the lights soon turned green and I drove off, 2 corners later I had lost the drive gear as I was turning a corner, it's as if I was in neutral. I came to a stop and noticed that the shifter moved very freely and that I had no reverse either. Park was OK.

I called the AA, and they plugged in their diagnostics tool and said there was an error code, "P2221 starter locking contact transmission temperature sensor signal implausible". The code wouldn't clear, so the car was trailered 30 miles to my local indy and I was recommended to start by checking the transmission fluid level.

A few days later the garage called me to collect the car. I asked if it was the transmission fluid (was only changed 4 months ago), and they said no. They had put the car up on a ramp to check the fluid when they noticed the gear linkage cable had snapped. They replaced the cable; and quickly checked the fluid level, which was bang on, great, a nice easy fix, or so I thought.

Driving the car home I was on the duel carriageway and the gearbox felt as if it had popped into neutral, not again I thought. As I was coasting, I tried putting the car into neutral and back into drive, but nothing, the car would rev as I pressed the accelerator but would not engage drive. As the car slowed down to around 5 MPH, all of a sudden the drive re-engaged and I managed to get myself home.

Today I took the car back down to the garage to explain what happened, however, on my way there it happened again.

I was driving along and it felt as if the car had dropped a couple of gears, causing rapid engine braking, a few miles later I lost all gears again, and again, as the car slowed down to around 5 MPH, it re-engaged and I got the car to my mechanic, a Mercedes indy.

They were at their lunch, so all the mechanics were in one room. I explained what had happened and how it was the same symptoms as before. They were all stumped, they said it wouldn't go into gear before because the linkage cable had snapped, and that it was strange that it had the same symptoms as before, but this time you managed to get the car going again. They said the new linkage cable wouldn't snap again and then reattach itself, and they couldn't think what would cause a similar problem.

I mentioned the sensor, but they dismissed that, and then someone said it might be bushes.
I plugged it into star and the only transmission fault is the temperature sensor.

Does anyone have any idea what could possibly be the problem or where to start?

Thanks
 
In the absence of any better ideas, I'd get the error code checked out. At the very least ask the garage to explain why they don't think it is relevant.
 
Update:

I have to drop my car off at the garage on Monday, so in the meantime, I plugged it into star to see if there were any more fault codes after losing gears again. Surprisingly, the "P2221 starter locking contact transmission temperature sensor signal implausible" error had not come back after I cleared it, so this is unlikely to be the cause of my problems, I looked a little deeper at what the scan uncovered.

I noticed ETC- electronic Transmission Control had a small f (as opposed to a capital F), I clicked on it and found stored error code P2500 - The transmission has an impermissible transmission ratio.

When I Googled the error code I got many different symptoms and repairs. I will see what my mechanic thinks on Monday.
 
Hello and welcome .

STAR tell you that there is a ATF temperature fault (real or imagined) would that not be enough to tell the transmission to shut down to save itself from harm ?

Does the car have a 5g or 7g transmission , I believe C215's could have been fitted with either.

It's a 5 speed (AMG Kompressor)
 
Well that box is a very strong transmission,the fault might be he electrical connection to the box,sometimes oil gets into it and problems occur,but any garage should be able to remove it and see if there is oil or a poor connection,hope you get it fixed soon.
 
I had this problem on my car also - Replacing the Contactor plate in the gearbox (with new solenoids too) fixed it. The gear speed detector is or has gone faulty and is registering an out of spec. reading for the expected internal gearbox speed.
I replaced the solenoids too, but this is probably not necessary (I just did as I was in there anyway) and, of course, a new oil filter, good clean of sump pan & the correct amount of new transmission fluid completed the sevicing of the gearbox which has been working perfectly ever since.
In my case, originally I drove into town - all perfectly normal until I stopped at a set of lights in order to turn right - and was first at the head of the queue. Lights changed, tried to move forward & no drive at all, forwards or backwards. Not helped by guy directly behind allowing 1 FemtoSecond of time (one quadrillionth of a second) before laying on the horn 🤬. Never wanted to punch someone out so Very, Very much. Some of the other nicer drivers went around me, through the lights, parked up & hot footed it back to help me push the car off the junction & round the corner to a safe parking place.
Sometimes, human nature can be a heart warming & humbling thing............ :)

gear speed sensor.jpg
 
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