klingsor

2013 S350, 116k miles on the odo.

I was driving at 15mph and went over a speed bump. As the car was climbing said bump, the car felt like it was shifting to Park and it lost all power. All dash lights came on. I stopped the car immediately and shut it off. Left it a couple minutes and started it again. It started fine, RPM is fine, no idling issues, no clicking noise no nothing, except for a solid check engine light. I shifted it to Drive and it drove fine for about 10 miles. Parked it overnight and started it again in the morning. CEL is still on but the car feels and drives ok.

So I had a freelancer with a generic scanner come visit me to scan it for codes and here is what the scanner spitted out:
P062700: The output for the fuel pump has an electrical fault or open circuit.
P008A00: The pressure in the fuel low pressure circuit is too low.
P008700: The fuel pressure in the system is too low
C146: No CAN message was received from control unit CGW.

What do you make of this? Can I drive the car until I have it looked at by the dealer? This wont be possible until mid next week so I want to be sure that I won't be damaging my engine. All inputs are appreciated.

Arrie

I don’t see how you could damage the engine with fuel delivery problems. The engine will just stop if it does not get fuel.

For the problem codes you have multiple codes indicating pump problems, which it could very well be but the last code indicates communications problem from the control module.

There should be no communication problem coming from the bad pump but you could get all other error codes because the communication problem will not allow messages to go thru so this may not be a pump problem at all and the codes indicating that may be faulty codes caused by the communication problems.

klingsor

Are you saying that the root cause may actually be in the last fault code?

The guy who ran the test asked me if I drove over a speed bump. I found it surprising he would ask that even though I didn't tell him how or when the CEL came on. He said driving hard over speed bumps can cause the fuel pump sensor to move and signal fault codes. He also said one of the codes indicates a fuel injection problem in addition to the fuel pump sensor. I also found that odd. Two weeks ago I started the car in the morning and the RPM shot up to 4,000 for 2 seconds before settling down to 900. I looked it up online and some MB owners reported that this symptom was related to bad injectors. Admittedly he isn't a mechanic. He just offered his opinion which I didn't take very seriously.

My primary concern at the moment is whether I could damage the engine by continuing to drive the car before I get it fixed. Glad to know that I don't have a catastrophic failure coming my way by driving the car before getting it fixed.

Arrie

Yes, I'm thinking when you get multiple codes like this the one triggering them is the one talking about communications issues. If you lose fuel pressure you should have only codes stating that. If you have communication issues then several checks don't clear and you get several codes.

Of course, it could be pump issue too but you say car drives fine, which kind of says you don't have fuel pressure problems.

klingsor

Quick update to those who may be reading this in the future for similar issues:

Two days later the check engine light disappeared and hasn't returned (yet). Sometimes upon hard acceleration the car would exhibit a minor loss of power, as if the car suddenly has 250hp. Regular accelerations, not so much. Still idles and shifts great.

Last thing: when the car is in Park and the A/C is turned off, I could hear a mechanical noise coming from the rear left quarter of the car. I couldn't figure out where exactly (inside the car or in the trunk), but it's there and it's similar to hearing loose stuff moving in the trunk.

I will have it checked out by the dealer next week and update this post for reference. If they change parts, I'll get the parts numbers as well.