Does the lite version of VCDS tell you which glow plug's bad?

Here's the code from VCDS-lite:

1 Fault Found:
17054 - Glow Plug Module 1; Glow Plug Circuit: Electrical Malfunction
P0670 - 35-10 - - - Intermittent

I didn't get more specific code telling me what exactly went wrong. Is it because I used a lite version (unregistered) or this code is the best the OBD can tell me? Thanks!

Glow Plug Circuit

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That is as specific as it gets. SOMEthing in the circuit isn't right. Now go find wingnuts sticky on glow plugs 101, grab your multimeter and dig in,

Thanks. I have the following readings:

GP#1: 0.6 ohm
GP#2: 0.6 ohm
GP#3: 0.9 ohm
GP#4: 0.2 ohm

I think GP#3 and #4 (round tip, so it's hard to steady the multimeter on it) are different than GP#1 and #2 (flat tip), and #3 and #4 look newer. Probably bc the previous owner only changed #3 and #4 but now #3 goes bad since its ohm is too far from #4. Anyways, the next to do is replacing all I guess?

Xuchen said:

Thanks. I have the following readings:

GP#1: 0.6 ohm
GP#2: 0.6 ohm
GP#3: 0.9 ohm
GP#4: 0.2 ohm

I think GP#3 and #4 (round tip, so it's hard to steady the multimeter on it) are different than GP#1 and #2 (flat tip), and #3 and #4 look newer. Probably bc the previous owner only changed #3 and #4 but now #3 goes bad since itughohm is too far from #4. Anyways, the next to do is replacing all I guess?

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Thems are good numbers. Start looking at your glow plug control module. i'm not sure how to test that though.

whitedog said:

Thems are good numbers. Start looking at your glow plug control module. i'm not sure how to test that though.

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I think someone said a difference of 0.5 ohm is good enough to trigger the CEL. So I'm more inclined to doubt the #3 and #4 glow plugs.

Pull them out, put them back in, retest. It would be better to be sure than to replace unneeded parts.

whitedog said:

Pull them out, put them back in, retest. It would be better to be sure than to replace unneeded parts.

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Can I pull them out and measure the resistance between the two ends? Or that I have to measure the resistance when they are back in the engine? Oftimes I found the biggest contributor to inconsistent measure is finding a good ground.

Yeah, measure from the tip to the threads. Reinstalling them will just show if there was resistance in the threads.

I turned out to replace #4 of 0.2 ohm with a new glow plug. It measured 0.8 ohm after installation. so all glow plugs are within 0.6~0.9 range. The CEL hasn't been on in the past week. Thanks for the suggestion!

Glad that fixed it. I am a fan of replacing all 4 glow plugs at a time as they all see the same amount of on time so the Mean Time To Failure will be be in a relatively tight time range. And then it is my empirical study that indicates that while resistance is a good screening mechanism for replacing glow plugs, testing them out of the car may show a glow plug that has high internal corrosion and does not heat up properly.

Yes I am an engineer/statistician.