OK it is my turn now with the glow plug not working.

My main question is should the glow plug be replaced right away or can I wait 3 months until the weather warms up a bit to change it myself ? Does runing an engine with one glow plug out hurt the engine or make the process of the long pencil type glow plug removal more problematic ?

The car starts and shakes a bit untill it warms up a bit then there are no more shaking. The glow plug indicator lamp stays on and the check engine light is on as well.

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2010 ML350 Bluetec
2012 Mustang Convertible

This happened to me as well, however, it was during the early summer in northern Ohio when the coolest temperatures are usually in the lower 50's. I went close to a month without any issue other than the lights on the dash. It is more an issue of living with it. The mystery question is whether one or more glow plugs may be close to going dead. If you loose a few more it could really become a pain.

As long as none of them break off replacing them is not that bad. It is takes time and patience. I did mine in six hours.

As long as it starts you are fine, however if it was causing a CE light I'd probably just bite the bullit and do it.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Test them and see which one(s) it is. If it's #1 you might be able to change it with the manifold in place.

Len

No. The glow plugs are a starting assist, and are not required for running. Any extra carbon initially deposited by a slightly cooler combustion chamber will likely go away during normal driving.

The most important fact to your motoring enjoyment is that is starts and can be driven.

The GP lamp is a reminder. You might want to find the cause of the CEL to be sure it is not another unrelated issue.

Thanks for the answers, OK, I did some more diagnosing and my code reader says error P0380, glow plug heating.

Taking sokoloff's advice, I tied to remove the No.1 GP wire to test the resistance and i could not reach it to pull the connector. I see it but I cannot get to it. I presume some parts needs to be removed to get to it.

I pulled the relay connector to GPs and five of the six test 0.5 to 1 ohms and one tests about 500 ohms, it is the top connector towrds the engine, black wire with green stripe, is that the No.1 ? If it is how do I get to it ?

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2010 ML350 Bluetec
2012 Mustang Convertible

The 500 ohm plug is bad. There should be a tiny number near each connector, and a diagram on the relay. Have a good look, it should make sense...

Look closely inside the connector you removed. There are tiny little numbers in there indicating which is which.

Len