EGR Codes

[Dieselfan]

4C87 Low pressure EGR cooler Plausibility
4CAE EGR controller

I have replaced the EGR cooler and the vacuum switch. But, to no avail. I then cleaned the EGR. No help neither.

What next? Please help.

[yemff]

you replaced the high pressure(front of engine) or low pressure egr cooler(on dpf)?

[robinasu]

Remind me, the LP EGR cooler is the one for the big turbo, correct? The LP EGR valve might be the root cause. If it's not actuating there will not be a temperature drop across the cooler when the valve is open. The LP EGR valve uses vacuum that is modulated by a pressure converter under the intake manifold to actuate the valve. Pretty common to have a leaking vacuum hose or dead pressure converter (vacuum control valve).

ISTA+ has test functions to exercise the EGR valves.

[Dieselfan]

Originally Posted by robinasu

Remind me, the LP EGR cooler is the one for the big turbo, correct? The LP EGR valve might be the root cause. If it's not actuating there will not be a temperature drop across the cooler when the valve is open. The LP EGR valve uses vacuum that is modulated by a pressure converter under the intake manifold to actuate the valve. Pretty common to have a leaking vacuum hose or dead pressure converter (vacuum control valve).

ISTA+ has test functions to exercise the EGR valves.

Thank you. I think you are right on the money. I found the spring broke on the LP EGR. Replaced the part but still the same issue.

So I bought a pressure converter. I will replace this part and let you know.

Stay tune

[Dieselfan]

Which is the low pressure?
https://www.realoem.com/bmw/enUS/sho...diagId=11_4270

[robinasu]

Number 14

[Dieselfan]

Originally Posted by robinasu

Number 14

Really?. So, I replaced #1 instead.
Damn. This is crazy.

Thank you for the reply.

[robinasu]

Originally Posted by Dieselfan

Thank you. I think you are right on the money. I found the spring broke on the LP EGR. Replaced the part but still the same issue.

So I bought a pressure converter. I will replace this part and let you know.

Stay tune

The above broken spring was going to cause codes at some point. Good to fix.

The way to remember which EGR is High/low is to use the connection to the DPF as reference. The HP cooler connects at the high pressure side of the DPF (entrance) and the LP connects at the DPF exit (low pressure side).

[robinasu]

Also be aware there is a specific bolt tightening sequence for the HP cooler for the best reliability. Might be worth a google.

Your LP EGR valve actuator is not moving and the valve feedback position sensor is complaining. Either you have a vacuum system problem or the pressure converter under the intake is not working. Those are the common problems. I suppose the EGR valve itself could be broken but the two above are most common. The vacuum hoses disintegrate.

[Dieselfan]

Originally Posted by robinasu

Also be aware there is a specific bolt tightening sequence for the HP cooler for the best reliability. Might be worth a google.

Your LP EGR valve actuator is not moving and the valve feedback position sensor is complaining. Either you have a vacuum system problem or the pressure converter under the intake is not working. Those are the common problems. I suppose the EGR valve itself could be broken but the two above are most common. The vacuum hoses disintegrate.

Didn't know there's a suggested sequence of bolt tightening for this thing LOL.
The Pressure converter under the intake has just been replaced and no dice there.
I have a new LP EGR in my hand and ready to swap it out. My question for you sir is... Is it doable for DYI guy? Do I have access to the nuts and bolts? I'm bit concerning.

Thank you again for your expert advise.