2006 E320 CDI Glow Plug Issue - PeachParts Mercedes-Benz Forum

rudydiesel · #1 04-07-2020, 04:43 AM

Hello astute members of the MB diesel community,

This is my first time posting on an automotive forum, so first off thank you for reading it. I have a 2006 Mercedes E320 CDI with the OM648 Inline-6. About 3 months ago, my eyes began to bask in the warm amber glow of a check engine light, unfortunately. I have a basic OBD-2 scan tool from Autozone and the code read P0671. Immediately, I went on to Amazon to order the correct Beru replacement glow plug for my vehicle. I then proceeded to replace said glow plug on cylinder #1. I fully expected to see the amber light to disappear, abracadabra, your owner is performing diesel magic, be gone! But alas, my trick did not work. The CEL light remains.

Here is the symptomology:
1. No noticeable engine performance maladaptive characteristics whatsoever. I do reside in central Texas where the average ambient temperatures are greater than a good portion of the country, but we had a few cold days here in January in which if there were to be signals of trouble upon cold start-up, none presented themselves.
2. CEL light on constantly with that singular pesky code of P0671, even as mentioned, after replacement of the cylinder 1 GP.
3. Sometimes, but not always, I get a GP dash error light in addition to the CEL light. The GP light always disappears after approximately 90 seconds while the CEL remains on, but I find it strange that the GP light doesn't present itself 100% of the time nor stay on constantly.

Hunches:
At this point, I think there is a likelihood that it could be the GP controller based upon my searches of this forum and others on the internet. But if indeed it is, why would I not be getting code P0670 to denote the assumed faultiness of GP module in addition to the P0671 that I am getting?

Question:
Any hypotheses of why I am getting P0671 Cylinder 1 Glow Plug Circuit DTC even after replacement with a new one, either confirming my current suspicion or presenting a new inference?

Disclaimer: I haven't checked anything with a multimeter yet. I know this is an important step to see if the new plug is functioning. I hope this doesn't preclude me from getting hypotheses from fellow forum members with erudite knowledge of the mechanical intricacies of MB Diesels. I will check the OHM's going to GP #1 when I change my oil within the next 2k miles.

shertex · #2 04-07-2020, 05:37 AM

Did you clear the code after replacing the plug?

engatwork · #3 04-07-2020, 07:27 AM

How many miles are on it?

ah-kay · #4 04-07-2020, 11:43 AM

You need to ohm out the old plug and the new plug first. I had the similar problem with my CDI but with faulty GP in cylinder 2 and 4 plus the controller communication.

This is what I recommend.

1) Make sure you know which cylinder is 1. It is the one nearest to the front of engine.
2) Ohm out old and new plug.
3) If old plug is good then it is the controller. The GP controller is known to have broken connectors internally, basically it melts with high amperage. It is made of aluminum. You can open it up and re-solder it. It is PITA but new one is $240 + change.
4) If the old plug is bad then the CEL light should go away.
5) Make sure the new one is Beru 5V GP.

dieselbenz1 · #5 04-07-2020, 12:13 PM

Check for voltage on #1 gp wire you should be getting 5v for a brief period.

Skid Row Joe · #6 04-08-2020, 12:50 AM

Quote:

Originally Posted by rudydiesel

Hello astute members of the MB diesel community,

This is my first time posting on an automotive forum, so first off thank you for reading it. I have a 2006 Mercedes E320 CDI with the OM648 Inline-6. About 3 months ago, my eyes began to bask in the warm amber glow of a check engine light, unfortunately. I have a basic OBD-2 scan tool from Autozone and the code read P0671. Immediately, I went on to Amazon to order the correct Beru replacement glow plug for my vehicle. I then proceeded to replace said glow plug on cylinder #1. I fully expected to see the amber light to disappear, abracadabra, your owner is performing diesel magic, be gone! But alas, my trick did not work. The CEL light remains.

Here is the symptomology:
1. No noticeable engine performance maladaptive characteristics whatsoever. I do reside in central Texas where the average ambient temperatures are greater than a good portion of the country, but we had a few cold days here in January in which if there were to be signals of trouble upon cold start-up, none presented themselves.
2. CEL light on constantly with that singular pesky code of P0671, even as mentioned, after replacement of the cylinder 1 GP.
3. Sometimes, but not always, I get a GP dash error light in addition to the CEL light. The GP light always disappears after approximately 90 seconds while the CEL remains on, but I find it strange that the GP light doesn't present itself 100% of the time nor stay on constantly.

Hunches:
At this point, I think there is a likelihood that it could be the GP controller based upon my searches of this forum and others on the internet. But if indeed it is, why would I not be getting code P0670 to denote the assumed faultiness of GP module in addition to the P0671 that I am getting?

Question:
Any hypotheses of why I am getting P0671 Cylinder 1 Glow Plug Circuit DTC even after replacement with a new one, either confirming my current suspicion or presenting a new inference?

Disclaimer: I haven't checked anything with a multimeter yet. I know this is an important step to see if the new plug is functioning. I hope this doesn't preclude me from getting hypotheses from fellow forum members with erudite knowledge of the mechanical intricacies of MB Diesels. I will check the OHM's going to GP #1 when I change my oil within the next 2k miles.

Quote:

Originally Posted by shertex

Did you clear the code after replacing the plug?

Quote:

Originally Posted by engatwork

How many miles are on it?

Quote:

Originally Posted by dieselbenz1

Check for voltage on #1 gp wire you should be getting 5v for a brief period.