I have a 2001 Mercedes C320.... Latley when idling, my car will just shut off. No harsh running, no choking. It just shuts off. After many attempts at restarting the vehicle it will finally start back up like nothing was wrong. The check engine light will remain on after i start it... After the vehicle has sat for 2-3 hours and the car is restarted, the engine light is off..

NOW...

Today on the way home im at a stop light, and my car just dies at the stop light, again, no choking...

However this time I noticed a warning light come on the says "BATTERY/ALTENATOR VISIT WORKSHOP!" it flashed in red and the went off. After about 10 minutes of turning the engine over it started as if there was no problem at all..

My first question is
If the altenator fails on this vehicle, will the car remain running off battery power or is it not like the old cars?

Does anyone have any ideas what this could be?

What can I check?

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2001 Mercedes-Benz C320 3.2
1991 Mercedes-Benz 300E 3.0

It will run until battery juice out,have someone check your alternator.

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MB STARS Master Guild Technician,17 years MB tech
14 years independent shop owner

Yes but will the altenator cause the car to just shut off without any signs?
The battery wasent dead, it turned over fast after it konked out.

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2001 Mercedes-Benz C320 3.2
1991 Mercedes-Benz 300E 3.0

I will read the code from your OBDII to start diagonstics why the engine shut off on you.

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MB STARS Master Guild Technician,17 years MB tech
14 years independent shop owner

How are you going to do that?

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2001 Mercedes-Benz C320 3.2
1991 Mercedes-Benz 300E 3.0

Goto AUTOZONE to have codes pull for free.

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MB STARS Master Guild Technician,17 years MB tech
14 years independent shop owner

I'd guess that the alternator light is a result of the engine shutdown, and not the cause. Find out what trouble codes are stored in the computer, and go from there.

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1989 300 SEL that mostly works, but needs TLC

I wish i had some way to pull the faults.

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2001 Mercedes-Benz C320 3.2
1991 Mercedes-Benz 300E 3.0

If your belt is fine and in good shape, your alternator isnt putting out enough to satisfy the ME control unit. take a voltage reading of the battery with the engine running, and again at 3000 rpm and report back.

The shutting off thing sounds like a bad crank sensor, especially if there are no codes.

My guesses without seeing the car: replace the voltage regulator on the alternator and replace the crank sensor and your problems will be fixed.

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1980 500SE/AMG Euro
1981 500SEL Euro
1982 380SEL
1983 300TD
1983 500SEC/AMG Euro
1984 500SEC
1984 300TD Euro
1986 190E 2.3-16
1986 190E 2.3
1987 300D
1997 C36 AMG
2003 C320T 4matic

past: 1969 280SE 4.5 | 1978 240D | 1978 300D | 1981 300SD | 1981 300SD | 1982 300CD | 1983 300CD | 1983 300SD | 1983 380SEC | 1984 300D | 1984 300D | 1984 300TD | 1984 500SEL | 1984 300SD | 1985 300D | 1986 300E | 1986 560SEL | 1986 560SEL/Carat | 1987 560SEC | 1991 300D 2.5 | 2006 R350

Where is the crank sensor located and is it easy to change?

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2001 Mercedes-Benz C320 3.2
1991 Mercedes-Benz 300E 3.0

Its on the drivers side of the engine, near the trans bellhousing, but still on the engine block. Kind of a pain to get to. You'll need an E8 socket to undo the bolt that holds it in.

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1980 500SE/AMG Euro
1981 500SEL Euro
1982 380SEL
1983 300TD
1983 500SEC/AMG Euro
1984 500SEC
1984 300TD Euro
1986 190E 2.3-16
1986 190E 2.3
1987 300D
1997 C36 AMG
2003 C320T 4matic

past: 1969 280SE 4.5 | 1978 240D | 1978 300D | 1981 300SD | 1981 300SD | 1982 300CD | 1983 300CD | 1983 300SD | 1983 380SEC | 1984 300D | 1984 300D | 1984 300TD | 1984 500SEL | 1984 300SD | 1985 300D | 1986 300E | 1986 560SEL | 1986 560SEL/Carat | 1987 560SEC | 1991 300D 2.5 | 2006 R350

John, Im glad you brought up the Crank Position Sensor. I work for VW, and everytime a VW has the problem my car is having, it is always the Crank Pos Sensor. Makes a lot of sense. i will go first thing in the morning to have the faults pulled.

What faults am I looking for?

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2001 Mercedes-Benz C320 3.2
1991 Mercedes-Benz 300E 3.0

As far as the crank sensor problem, it might not have set any faults. 90% of the time it won't. I'm not sure if the regulator will set a code or not, but if you got a battery message in the cluster, it had to have set something. Get a printout of what your codes are and post it.

What are the voltage readings on your battery with it off, running, and at 3K??

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1980 500SE/AMG Euro
1981 500SEL Euro
1982 380SEL
1983 300TD
1983 500SEC/AMG Euro
1984 500SEC
1984 300TD Euro
1986 190E 2.3-16
1986 190E 2.3
1987 300D
1997 C36 AMG
2003 C320T 4matic

past: 1969 280SE 4.5 | 1978 240D | 1978 300D | 1981 300SD | 1981 300SD | 1982 300CD | 1983 300CD | 1983 300SD | 1983 380SEC | 1984 300D | 1984 300D | 1984 300TD | 1984 500SEL | 1984 300SD | 1985 300D | 1986 300E | 1986 560SEL | 1986 560SEL/Carat | 1987 560SEC | 1991 300D 2.5 | 2006 R350

Yea, after my car acts up and i let it sit and cool, usually the light is off. I wonder if it automatically sets readiness code.

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2001 Mercedes-Benz C320 3.2
1991 Mercedes-Benz 300E 3.0

Is your car built before 07/01 or after? The pre 07/01 eng m112 had a problem with the connector on the crank sensor, not sealing and allows moisture in. There's an updated plug available, p/n A 112 150 01 33

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