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I have been having some trouble with cold starts lately. I will be replacing the crank sensor as soon as new one arrives but in the mean time i have been trying my glow plugs.

I bought some replacement ones, (cheap naff fleabay, dont start..!) and they have a resistance of 1.5/1.6 Ohms this seems a bit high and has been giving me a glow plug error on the dash.

The old bosch ones i removed (which onced cleaned up look fine and may well go back in) read around 1.1 Ohms. This still seems a little high still but better than the others as lower resistance means more current > more heat.

My question is... can anyone confirm what they should read brand new/functioning correctly? I estimate this should be around 0.7 Ohms? If so is this what a brand new set of Bosch ones read?
 

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Whilst we're on the topic, stay away from cheap ebay imatations. Go for brands you have heard of!

When i was fitting one of these cheap glow plugs it sheared as i was tightening (under the torque spec). Everyone had warned me of the danger of the old ones snapping in the head when removing, but i did not expect one to snap on the way in! Luckily i was able to carefully drill the head part out and simply pull the core out without damaging the threads or needing to spend more money.
 
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Hi,
I've just had the flashing glow plug warning light on my 2.4 JTDm. When the glow plugs fail they go high resistance. Not just slightly, but completely (ie open circuit). I checked mine - they're between 1 and 2 ohms - the resistance of your multimeter test probes and dirtiness of the metal contact will make the biggest difference to the readings - I wouldn't get picky over half an Ohm. The dead one was open circuit! The Bosch glow plugs on mine (Bosch Part: 0 250 203 001) are also capable of a thing called "afterglow" where after the initial starting, the plugs are active to reduce diesel clatter and improve emissions for a short while after the engine starts. I wouldn't recommend cheap ones and would replace like with like. I used "The Green Spark Plug Company" who seem very good. Oh yes, don't bother replacing them as a set - they are not spark plugs - you wouldn't replace all the bulbs in your chandalier if one went, would you?
If *all* your BOSCH glow plugs have resisitance of a couple of Ohms I'd put my money on the glow plug control unit.

Best of luck with it!
 
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