Limp mode and code po405

dannyfiveforty

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My w221 has gone into limp mode and shows the code po405(see attached picture) I have read on a smart car page that this code is sometimes thrown up due to a clogged egr valve. Has anyone else had an experience with this code on a cdi?

I cleared the fault but it came back within Two miles..

Thanks
 

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Botus

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P0405 Exhaust Gas Recirculation Sensor A Circuit Low

there's been quite a few failures of late (designed to fail !!!) with people referring to an "exhaust back pressure sensor" ... I can image this is linked to the turbo wastegate and the EGR valve doing there bits correctly....

circuit low sounds like wherever the EGR sensor is, its popped
 

mattkh

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A160 W168 1999 1.6
"I have read on a smart car page that this code is sometimes thrown up due to a clogged egr valve."
Hi
The clue to this error is the use of the word "circuit".
It refers to the voltage as checked at the plug connected to the EGR valve.
I think it is an electrical fault.
 
OP
dannyfiveforty

dannyfiveforty

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Many thanks, yes does seem to make more sense to be electronic. I cleared the fault and managed perhaps 20 miles or so this time. It has come back again this time with an eml.

One other thing I have noticed since this is when I switch engine off the car now has a diesel shudder, a slight shake as the engine stops rotating, older diesel cars and some lorries used to get it.

Could this be related or coincidence??

Many thanks
 

mattkh

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Many thanks, yes does seem to make more sense to be electronic.
Could this be related or coincidence??
Many thanks
Hi
I think it is 'electrical' rather than electronic. If the electrical connector to the EGR is accessible, I would check the condition of the wires and then check the voltage.
My diesel knowledge is limited.
 
OP
dannyfiveforty

dannyfiveforty

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To update, I ordered a new egr valve and all is well. I guess a build up of carbon burns the motor out and give readings that are then out of parameters.

Thanks
 


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