W251 R-Class EGR Issues

[ber5ien]

When the EGR connector is removed, there should be nothing on pin 5. This means that wires 3 and 5 have a short circuit. There are only two power supplies 12V and 5V, you have 3.

Disconnected plug from ecu and checked for continuity’s.

EGR pin 3 ecu pin 56 ok beep
EGR 5 ecu pin 18 ok beep

Then
EGR pin 3 ecu pin 18 no beep
EGR pin 5 ecu pin 56 no beep

 

[ber5ien]

Many thanks for all your help but I am giving up decided to have it disabled by tuner.

I have unwind all the wiring from ECU to EGR. Pretty much moved everything so if there would be any cables touching it either they would definitely move position a bit.

I would imagine that one of the other part is causing issue on that line.

The EGR still is stuck on 0%.

2 EGR tried (both OEM)
1 new back pressure sensor
1 cable to back pressure sensor
Fixed oil leak in the vacuum pump ( also checked connector from valve to see if there oil there)
Checked EGR valve solenoid (all good it clicks). Tested with 12v battery

STAR does not show any other errors apart from EGR valve and those two codes.

 

[Mersovod]

I would first check the accuracy of all the sensors that the ECU uses to control the EGR.

 

[ber5ien]

Thanks. I will get a reading from these.

Left hot film mass air flow sensor (B2/6)
Intake air temperature sensor (B2/6b1)
Right hot film mass air flow sensor (B2/7)
Intake air temperature sensor (B2/7b1)
Boost pressure sensor (B5/1)
Charge air temperature sensor (B17/8)
Pressure sensor downstream of air filter (B28/5)
Accelerator pedal sensor (B37)
Crankshaft Hall sensor (B70)