w204 C220 CDI Camshaft Position Sensor P0340

[starrzo]

It has actually happened both hot and cold

Actually, occasionally when I try to start the car nothing happens when I turn the key....all lights and everything normal in the ignition position, then nothing when I try to crank. Only way to get it to work is remove the key and turn again.

Not sure if that's related at all though

 

[starrzo]

Thing is, those sensors never go wrong, and are only used on cranking, once the engine is running, they bear no relevance, it only measures the crank sensor. You can disconnect it when running and the engine will still run.

Are you talking about a crankshaft sensor, as opposed to camshaft? Or are they interdependent?

 

[Steve@Avantgarde]

First thing, I would get a STAR diagnosis test done, that way you can confirm your fault.

Secondly, the camshaft sensors very rarely go wrong, I think I have only replaced 2 in my whole 15 years working on Benz products. I have seen a lot of broken wiring plugs to that sensor where they go brittle or people break the clip and then just push fit it back onto the sensor. It causes a loose contact.

Thirdly the cam sensor only is required on cranking, once the engine is running, you can disconnect it and the engine will carry on running. The crank sensor is required all of the time though.

You have an early 204 and you say you are getting nothing when you twist the key to crank the engine - I would say you have the makings of a failing steering lock, which is ever so common.

 

[starrzo]

First thing, I would get a STAR diagnosis test done, that way you can confirm your fault.

Secondly, the camshaft sensors very rarely go wrong, I think I have only replaced 2 in my whole 15 years working on Benz products. I have seen a lot of broken wiring plugs to that sensor where they go brittle or people break the clip and then just push fit it back onto the sensor. It causes a loose contact.

Thirdly the cam sensor only is required on cranking, once the engine is running, you can disconnect it and the engine will carry on running. The crank sensor is required all of the time though.

You have an early 204 and you say you are getting nothing when you twist the key to crank the engine - I would say you have the makings of a failing steering lock, which is ever so common.

Thanks for your advice - I appreciate it.

One question - you say the camshaft sensor is only required on cranking, and that the car will keep running if it is disconnected....but does the ECU still use values from it while the engine is running, but it just isn't necessary?

I'm just wondering, since the engine light came on at 60mph after about 15 minutes of driving. It might be a good indication that I've got an incorrect or unrelated error code if the camshaft sensor wasn't even being used.

Cheers!

 

[Yugguy]

I think you need to get it to a Indy with a reader. Or the icarsoft i980 is about 90 quid in eBay.

 

[Steve@Avantgarde]

Once the engine is started, the ECU doesnt need its signal, you can see this on actual values on STAR, once its started, it becomes dormant, the engine is running, the camshafts must be turning, the crank sensors provides the running signal.

 

[starrzo]

Hey, just an update on this.

On your recommendation I bought an iCarsoft i980. Also, last week I replaced the camshaft sensor because my engine light came back on (P0340 read with my cheap dongle) and I was still waiting for the i980 to arrive.

I also checked the plug going to the sensor - looks perfectly fine, and I also tested the cable ends with a multimeter which read a perfect 5 volts on the switch and power cables and a good earth on the other.

The i980 arrived today, and I've got two of these codes:

What do you guys reckon? Is it safe to assume my camshaft sensor was bad?

Cheers!

 

[umblecumbuz]

What is the second code?

If you make a note of both codes, then delete them, you will get a clearer idea if, after driving the car, either code returns.

Umble.

 

[starrzo]

What is the second code?

If you make a note of both codes, then delete them, you will get a clearer idea if, after driving the car, either code returns.

Umble.

Both the same code.

 

[jareitio]

Hello.
I've a 2008 w204 c220 om646 with the same problem I think.
Did you solve your problem? How?
A month ago I changed the thermostat because it never reached 92 degrees.
Since then, when the car reaches the temperature of 92 degrees, if I acelerate strongly the engine light is turned on. If I acelerate the car slowly until the car is hot (20 or 30 miles) no errors appear.
The code errors are P0340, P0341, P200B and P200C. I reset the errors with the torque application and does not return the error until the next day when the car is cold. With the hot car never gives the error.

 

[Stuart Perryman]

Was there a solution to this? I have the same issue with cam sensor error code after thermostat change and when accelerating after getting up to temperature. Old pics aren't showing on this thread so can someone post the location of the camshaft position sensor a on the engine please. My initial thoughts are its something caused by engine running cold with bad thermostat for a few months and now getting to temperature has damaged the sensor and hoping it isn't an issue with the chain. Engine runs fine it just started throwing the fault after the thermostat change

 

[Mizgan Adrian]

Hi there,
Starrzo, i have literally the same problem as you. What was the solution?

 

[Ras204]

Morning,

Did anyone find a solution to this? I have just started experiencing the same issue post thermostat change. Mine flags when running at steady state usually around 70mph on dual carriage way. No change in engine behaviour from it.

As some others have said the camshaft is only used during starting which would make sense if the engine has no variable camshaft timing.

Due to this my theory is that the timing chain could be stretched or the tensioner is worn from running cold. I guess the OBD looks at cam position during steady running once warm to check for chain issues?

 

[Justinian]

Morning, P0340 after thermostat change. Car runs fine on 92C. It was running cold for some unknown time. Oil changed no shavings. Ordered new sensor.
Can this be caused by the thermostat change? Crazy. Anyone.....

 

[Justinian]

Update: Just replaced the sensor no more fault. Strange how this happened after thermostat change. all god now.

 

[Ras204]

Update: Also changed the camshaft position sensor, had no fault codes after over 500 miles of driving (Taken a while due to lockdown). Worth noting I tried a cheap one and the car didn’t always start first time, replaced with an OEM one and it’s been okay since.

As for the fact it flags post thermostat change I suspect this is due to the OBD check of the signal is only carried out when the coolant is up to temperature.

 

[Maico490]

Hi all,
I'm new here but had the P0340 error on my 2008 w204 with the OM646.811.
Any hard acceleration especially if it made the gearbox kickdown would bring on the EML with P0340. I fitted a new camshaft sensor after testing the wiring and no more light. It seems that the ecu may not monitor the camshaft all the time but the signal is checked under certain conditions.
Sensor fitted was an aftermarket Febi Bilstein.
Looking forward to finding out more here.
Mike

 

[starrzo]

Hey, sorry it's always annoying when someone disappears from a discussion after finding a solution. Many years later and the car is still running very nicely after the camshaft position sensor and thermostat change. It's also still running at around 92 degrees also.

I used MB genuine parts from a dealer.

 

[Threepointingstar]

Hey guys!
I got myself a 2008 C220 CDI s204 with the OM646 engine. After 1000km done with it, the engine light came on in the highway on my way to the mechanic to do the gearbox maintenance.
Received call saying it was the P0340 code, with camshaft and crankshaft sensors not reading well.
The mechanic says it can be one of 3:
1 - sensors
2 - timing chain
3 - flywheel
Mechanic said it is unlikely that the issue comes from the sensors as it’s both of them, but let’s see tomorrow what the issue is

 

[Threepointingstar]

Hey guys!
I got myself a 2008 C220 CDI s204 with the OM646 engine. After 1000km done with it, the engine light came on in the highway on my way to the mechanic to do the gearbox maintenance.
Received call saying it was the P0340 code, with camshaft and crankshaft sensors not reading well.
The mechanic says it can be one of 3:
1 - sensors
2 - timing chain
3 - flywheel
Mechanic said it is unlikely that the issue comes from the sensors as it’s both of them, but let’s see tomorrow what the issue is

Quick update: the next morning the error wasn’t there anymore.
Anyway, the sensors where changed waiting for a feedback on the rest of the components that can cause the problem