This C300 (W205) has been doing this thing where it loses acceleration then jerks forward while driving for several months. I replaced the spark plugs on it, but the problem remained.

I read that this symptom gets worse until the sensor that causes this issue totally fails leading to a non start situation. I have now had a shop diagnose the problem to male sure it is what I thought is causing this issue. After the diagnosis and testing of the crankshaft position sensor, the mechanic has informed me that it is indeed the crankshaft sensor that is causing this and gave me a price to replace the sensor - $150 for the sensor plus two hours labor to remove the shields under the car, some other part that is in the way and finally the sensor, then put everything back. After paying for the diagnosis, he was to order an OEM sensor.

Afterwards he claimed he was talking to a mechanic friend of his who told him that, to gain access to the sensor, the job requires removal of the catalytic converter and disconnection of the prop shaft and that the expensive catalytic converter clamps and gaskets need to be replaced as well, for a total of 4-5 labor hours.

This mechanic has obviously never done this exact job, but I know that he gets loads of German cars in his shop. Has anyone done this job or had it done at a shop? Is all this stuff about the level of difficulty true? What is a fair labor charge in hours to do this job?

flopper

 

Problem solved.

Took the car to a different shop that specializes in European imports. That shop diagnosed the symptoms with an advanced diagnostic tool. Even though the Check Engine Light was not illuminated, they found eight codes stored in the PCM !!!

They recommended replacing the crankshaft sensor as well as the turbo pressure transducer. The crankshaft sensor is buried deep in the lower back bowels of the engine on this particular model and quite difficult to get at it, but no part of the exhaust system needs to be removed to replace the sensor. The car is driving smoothly again after replacing those two parts and clearing all the codes from the PCM.

This shop charged 2.5 hours labor to diagnose the problem and replace the two parts.

It helps to go to a shop where the mechanics know what they are doing. My gut told me the first shop didn't have a clue. I am glad I listened to my gut! Unfortunately the first shop charged for their semi faulty diagnosis.

Hope this helps others with a similar problem.

 

An update.

I messaged the first shop, pointing out what I did to get the car repaired. That shop then offered to give back the money it had charged for its diagnosis, maintaining that its diagnosis was correct! I had told them I thought it was the crankshaft position sensor by what I had read!

I did NOT tell them this, but the shop that repaired the car said to me that it would have been impossible for anyone to test the crankshaft position sensor without taking it out, given how deeply buried it was, and that nobody had taken it it out!

Consumer beware!