Today’s Symptoms:

Got this 2004 Mercedes c240 no start problem today. Car was running fine and suddenly quit. When ATS customer scanned the codes, he got P0335 code which stands for crank sensor “A” circuit fault. He is now asking if the crank sensor is faulty and if he needs to reprogram the engine computer to make it work? Engine size is 2.6L V6.

Diagnostics for 2004 Mercedes c240 no start:

I was just reading the common fix for this fault code and it seems the crank sensor is the usual culprit. You can check from the dealer if they stock it a lot. Furthermore, looking at the wiring diagram, this sensor is located at the top back of the engine by the flywheel housing pointing to the flexplate if you have an automatic tranny. There are only 2 wires going to it which all connect to the engine control module or ecm. MB calls them ME-SFI and this ecm is located on the left rear of the engine compartment.

Testing the crank sensor for 2004 Mercedes c240 no start:

Start with the basics: do you have spark? If you do… you can almost discount the crank sensor to be the culprit. If no spark, then proceed to check the 2 wires going to the sensor namely: green and green white color wires. Check for continuity from the sensor to ecm. Each wire should have less than 5 ohms of resistance, if higher expect some bad short in the wires. Both wires will probably carry a tiny AC voltage which can only be tested by labscope so there is no point in testing it with your digital voltmeter.

You can also remove the crank sensor and visually check the sensor probe end for signs of rubbing. On some MB service bulletins, it mentions about putting a shim so it does not rub the flexplate gear. If good, I would just go ahead and replace this crank sensor.

As per database, this is just a straight forward R&R (remove and replace). The ecm does not have to be reprogrammed after the crank sensor replacement. The old fault code must be erased though after the crank sensor replacement by using a scanner. Watch also that on some MB models (please verify with MB parts dealer), there are 2 crank and 2 cam sensors for every engine. Just make sure you are replacing both crank sensors when doing this. However, looking closer at the wiring diagraml, this engine only shows one crank sensor.

Note:

This same message was sent to ATS customer and I am now waiting for the result of the repair. I will keep you posted soon but you can leave your comments below if you have any 2004 Mercedes c240 no start concerns.

Thanks,

Richard