M112 320 difficulty starting when hot and P0341 code - Cam or Crank position sensor? Or something else.

[MarkCorrigansBoiler]

Hello,

I usually use my car for shortish journeys but did a long journey of 2.5 hours recently. After stopping for petrol after about an hour, my 2003 W209 CLK320 (petrol) threw a Check Engine Light but otherwise ran fine. After stopping again later, the car would crank over fine, but would not start, after a few more minutes, I tried it again and it started and drove fine. The same thing just occurred on the drive home (after stopping after a couple of hour and trying to restart, it would crank, but not start. After a few minutes, it started and drove fine.)

I pulled the codes and the only one stored was a P0341 which indicates "Camshaft Position Sensor A Circuit Range/Performance Bank 1 or Single Sensor"

I've done a whole bunch of searching and reading and I'm a bit confused. Sue to the similarities in name, a lot of people seem to be confusing the Cam Position Sensor and the Crank Position sensor.

Do the symptoms I describe sound like the Cam (as indicated by the code) or the Crank sensor is at fault? The Internet seems to suggest the Crank being a more common fault and matches my symptoms, but the P0341 code suggests the Cam sensor.

Any help appreciated.

I'm hoping for the Cam as it looks like an easier part to replace on the M112 Thanks.

 

[Petrol Pete]

TBH you are looking at about £100 (or less) for all 3 sensors . On a 19 year old car . I would just replace them all. Pretty straightforward DIY job.

Crank sensor. A bit fiddly to get to .

Cam sensor(s)

 

[Bellow]

Crank position sensors when they fail tend to stop a hot engine when it is idling - eg, at a junction.
Cam position sensors are usually there to enable starting (the ECU cannot tell compression from exhaust stroke from crank position sensor alone).

 

[MarkCorrigansBoiler]

Thanks for the replies so far.

I hear what you're saying about doing them all, but I'm limited in time and skill so I think I might tackle the cam sensor first as it looks pretty straighforward. Now I just need to find somewhere selling the proper Bosch ones, I've seen mixed results from off-brand parts on this car.

 

[Bellow]

Given that the problem occurred immediately after re-fuelling, check that the filler cap is secure and not causing an EVAP problem. There's a very low probability of that but as it only takes seconds to do...

I agree, cam position sensor first.

 

[DrNick]

Yea, try the cam sensor first as
A) the code pointed at it
B) it’s easy
C) crank sensors, although easy in principle, are usually difficult to get to and can be, shall we say, exciting to remove.

 

[MarkCorrigansBoiler]

I've ordered the sensor, just waiting on delivery.

I'm assuming I should disconnect the battery negative before replacing the sensor? I normally would, but none of the guides I've seen mention doing that, and it would be good not to lose the radio/trip data if I don't have to.

Either way, I'll let you know how I get on.

 

[Bellow]

I've ordered the sensor, just waiting on delivery.

I'm assuming I should disconnect the battery negative before replacing the sensor? I normally would, but none of the guides I've seen mention doing that, and it would be good not to lose the radio/trip data if I don't have to.

Either way, I'll let you know how I get on.

No need to disconnect battery - the sensor will be dead with ignition off and as you say, no point in losing codes, adaptations, etc.

 

[MarkCorrigansBoiler]

Great, thanks. That's saved me some pain

 

[MarkCorrigansBoiler]

The cam sensor finally showed up and I've replaced it, I love an excuse to use my 1/4" torque wrench. The new sensor design looks a little different and the new (Bosch) one looks ever so slightly shorter than the existing (MB branded) one. Even so, the car starts and runs fine and after I cleared the codes, nothing new has been logged. A long journey will be the real test, but I won't be doing one of those for a couple of weeks.

Thanks again for your help thus far.