Failing SAM module??

[Ovlov440]

Hi all

Bit of an odd one but maybe someone has the knowledge.

Today, when calling on kickdown in my 2014 W218 CLS the car went into limp mode. This has happened before after which the Quantity Control Valve on the HPFP was replaced.

When I got to a set of lights I turned the engine off and non. The EML stayed lit (normal behaviour after throwing a code) but then the car also decided the parking brake was on, the bonnet was open and that it was dark (headlights came on). Drove home. I went out and hour later, no issues at all.

To add to the weirdness a couple of months ago I got the battery warning message on the dash. Having recently replaced the auxillary battery in the boot I replaced the main battery as it was reading 11.9v. With a new battery fitted I still kept getting the warning light for another 6 weeks, until it just stopped, that is until it flashed up 4 times yesterday!

I am thinking this is all related somehow so a junction box/SAM unit seems like a likely culprit?

A code read only shows P0087 relating to the EML.

Any thoughts/guidance appreciated.

Thanks

Ade

 

[markjay]

You really need to get the codes read by STAR (or iCarsoft, if DIY), because generic OBDII scanners won't tell you much.

(Incidentally, the code you mentioned is linked to the fuel delivery system, which is a known weakness of high-pressure Diesel engines, but you didn't say if your car had Diesel engine)

 

[Ovlov440]

You really need to get the codes read by STAR (or iCarsoft, if DIY), because generic OBDII scanners won't tell you much.

(Incidentally, the code you mentioned is linked to the fuel delivery system, which is a known weakness of high-pressure Diesel engines, but you didn't say if your car had Diesel engine)

Hi, yes it's the 250d engine. New fuel filter and QCV. Only thing I can think of now is the lift pump in the tank.

 

[markjay]

Hi, yes it's the 250d engine. New fuel filter and QCV. Only thing I can think of now is the lift pump in the tank.

I suggest that you get it checked with STAR.

The high pressure Diesel pump is quite expensive and you don't want to replace it unless you have to. Also, the new fuel filter might be the issue (if the fault only appeared after it was replaced).

Additionally, on these cars, the AdBlue system and NOx sensors are also a known weakness, so get the codes read properly before changing more parts.

 

[Ovlov440]

I suggest that you get it checked with STAR.

The high pressure Diesel pump is quite expensive and you don't want to replace it unless you have to. Also, the new fuel filter might be the issue (if the fault only appeared after it was replaced).

Additionally, on these cars, the AdBlue system and NOx sensors are also a known weakness, so get the codes read properly before changing more parts.

P0087 was being thrown every 3-4 months before the fuel filter was changed, same afterwards.
Car is 2014 with no ad-blu (deliberate choice!). Local Merc specialist has read the codes and nothing specific comes up - just P0087 relating to low fuel rail pressure.
It's an irritating issue as it sometimes happens, but other times kick down is fine and the car accelerates cleanly.

I am wondering if a faulty SAM module could be linked to all the symptoms I have experienced (low fuel rail pressure, battery warning light, hood open warning, parking brake on warning, lights coming on when its daylight)?