P0380 but glow plugs OK? - PeachParts Mercedes-Benz Forum

VW1300 · #1 05-07-2013, 07:21 PM

I have a CEL and code P0380. Searching this forum points to the glow system. The glow light comes on for about 5 seconds or so before starting, and the car starts easily when it goes off. The glow light stays off, but the code has come back several times now after I cleared it (I thought maybe I didn't let the plugs glow long enough before driving, but I doubt that now).

I pulled the plug that goes into the relay socket and tested the continuity of each plug. They all show 1.0 ohm. So they seem OK.

What do I check next? Could my relay be getting flaky? Or can P0380 mean something else?

Thanks,

Diesel911 · #2 05-07-2013, 08:25 PM

P0380 Glow Plug/Heater Circuit "A" Malfunction came from the below site. I don't know what Circuit "A" is and I don't know if it means the code covers the Glow Plugs and the Heater or they are saying the Glow Plugs are considered a Heater????

Mercedes Error codes - MBWorld.org Forums

Diesel911 · #3 05-07-2013, 08:29 PM

P0380 Glow Plug/Heater Circuit "A" Malfunction came from the below site.

I don't know what Circuit "A" is and I don't know if it means the code covers the Glow Plugs and the Heater or they are saying the Glow Plugs are considered a Heater????

Mercedes Error codes - MBWorld.org Forums

VW1300 · #4 05-08-2013, 08:40 AM

Had a buddy hold a multimeter onto a relay output spade while I started the car. The relay put out 12V when the key was in the "run" position, but went off once the car started. I believe the relay is supposed to stay on for a few minutes after the car starts, so that points to a relay issue.

Engine was warm when we did this, but the relay isn't smart enough to adjust the glow time to the engine bay temp is it?

Diesel911 · #5 05-08-2013, 09:31 AM

You could repeat the test with the Engine Cold.

However, if it was working normal the Code would not come on.

I don't know enough to help and the Online Manual I have access to does not cover your year and Model.
A few People have said that you can access some of the Mercedes Manuals on Startek but I believe you need to register with them to access the Manuals.

TMAllison · #6 05-08-2013, 10:51 AM

The relay ought to stay on for a minute or two after starting. Thats probably what is throwing the PO380 fault. Better scanners will throw P1365, 66 & 67 for bad GP's. That would be cyl 1/2, 3/4 & 5/6 respectively.

VW1300 · #7 05-08-2013, 10:31 PM

Thanks. I ordered a new relay from Pelican, will post once I get it in and see if the codes go away. I spent a little time tonight replacing the rear sway links in hopes of getting rid of a thunk whenever I hit a bump.

VW1300 · #8 05-19-2013, 10:47 PM

UPDATE: After being on for over a week, the check engine light went off. I replaced the glow relay anyway (it had already arrived) a little over a week ago, and it's still off. Given that it was not completely dead before I replaced it, I think I need to go another month or two with no more P0380, and then I'll consider this a success. Next job, rear LCA bushings. Waiting on the removal tool from another forum member.