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New Member
Jan 22, 2015
w204 c180
I've selected wiring and electrics- hopefully this is the correct heading - not sure.

Anyway, I've had a 2012 W207 cdi 250 coupe for almost three years. Very low miles and bought as a cat D with light glance across front bumper. Front legs were knocked over by about 60mm, but I only replaced the ally extension to the bumper bar on the right side. Everything else original and pulled. Remaining damage was superficial/ paint. Been driving it up until march 20 when the mot expired and Covid happened. Hence needs a new ticket. In January, I noticed a couple of times the dashboard saying ACTIVE BONNET MALFUNCTION. It seemed intermittent at first but then stayed on. I have finally got around to looking at it. I put a foxwell scanner on it and it comes up code D18/ MIL ON stored and current. Description is : Communication with the right sensor for function active engine hood has a malfunction. Luckily I have access to another W207. So far I have swopped out the right hand sensor bolted to the bumper bar and also the right hand bonnet catch with the sensor, check the wiring for obvious damage etc. My parts work without fault in the 350. If I disconnect the right sensor from the loom I get an SRS restraint system fault as well- hence the system seems to recognise if the sensor is there or not. I can erase the code and the dashboard notice goes, but returns within five seconds. I'M NOW STUMPED and nothing usually does !! I've been around the block a few times ! Regarding Mercedes wiring quality it's not great on the other W207 ( the 350) he had problems with nothing gradually working on the bootlid. Ie, unlocking, number plate lights not working etc, etc. On investigation in the boot we found the wires in the loom had mostly snapped or were hanging by a thread beside the hinge. Out of 11 wires we had to piece out 9 of them. Hence I query the quality of Merc wiring. I'm unable to do a full continuity test with a meter since I don't know where the other end of the accelerator sensor wires terminate ?


NB, the front damage three years ago was a light sideswipe - no airbags, pretensioners or active bonnet were fired. IE, NO SRS reset required at the time. Thanks.... Keith ( Hampshire)
Battery fully charged (ie tested under load)?
Battery fully charged (ie tested under load)?
The honest answer is original battery. It has depleted having been sat in garage for three months and only just turned engine over. I gave it a slow charge over 24 hours. Holds up at 12.6 volts, spins 250 cdi lump over easily enough. Why would this cause my probs ?
What ! No techy's out there with a suggestion. Could it be the actual hinge sprung mechanism ? That's the only item I haven't swopped yet.
I didn't read this carefully enough first time... I thought you swapped hinge actuator but it was bumber sensor... I am getting also intermittent active bonnet message and MY SDS pinpointed right hinge actuator... must be moisture/corrosion/wear on wires or just failing actuator. What I have read its not very uncommon part to fail, I just haven't repaired it yet because in summer times it works.

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