Nick Mumby

Hi,

a few weeks ago on a long run, the slk started running rough. It felt like it was only running on 5 cylinders. I scanned it and sure enough the errors were;

p0305 - Cylinder 5 Five Misfire Detected
p0629 - Fuel Pump "A" Control Circuit High
p0653 - Sensor Reference Voltage "B" Circuit High

Restarting the car temporarily cured it.

I've had a couple of cars in the past with fault coil packs, and this felt like the same problem. I bought a replacement Delphi for about £20.

I didn't get round to fitting it for a couple of weeks, but the car was running fine.
the other day it spluttered a bit, so I thought I better get the part swapped in. The car didn't show the CEL or go into permanent running rough this time.

I've now got the new coil pack in, but still getting a few 'pending errors'.

P0102 - mass or volume circuit low input
p0629 - Fuel Pump "A" Control Circuit High
p0653 - Sensor Reference Voltage "B" Circuit High

the sound like they could all be caused by a misfire.

I've only run the car for a couple of days since the new coil pack and haven't had any running issues yet. Just the stored codes.

any ideas?

cadeca

Nick, you might want to post this over on SLKWorld.com since there seems to be more R171 traffic there. Good luck in resolving the codes!

nugent

My 2008 E350 has the exact same codes and symptoms you had:
p0305 - Cylinder 5 Five Misfire Detected
p0629 - Fuel Pump "A" Control Circuit High
p0653 - Sensor Reference Voltage "B" Circuit High

Did you get this sorted? If so, how?