CDTI Spanner light after cold starts

[Teapot]

About a month ago, the spanner light started appearing after a cold start, and then extinguishing after about 3-4 minutes. I suspected a glow plug had failed, so I tested the resistance of each plug. Three of them were about 1 ohm, whereas one was high resistance, so clearly failed.

I replaced all the glow plugs with new ones, but even after several days the spanner light was still coming on. I've tested them again in case of one of the new plugs being bad, but they all read about 1 ohm.

Does the ECU have to be 'reset' to clear the spanner light, or is there possibly another fault lurking?

The car is a 2004 signum 1.9cdti.

cheers,
Paul.

[LADmachining]

If the fault has been cured, the spanner light will be extinguished, but the fault code will remain the ECU, but 'not present', for 30 ignition on/off cycles.

The glow plug control unit, the finned silver box next to the battery, is known to cause problems also.

[mparks8590]

if it hasn't been done, you could change the fuel filter

this can also chuck up the spanner light sometimes

otherwise is it driving ok?

[Teapot]

if it hasn't been done, you could change the fuel filter

this can also chuck up the spanner light sometimes

otherwise is it driving ok?

Ah good point - It's been about 18 months and 15k miles since I last changed the fuel filter. Will try that first.

It starts and runs fine in all other ways.

cheers,
Paul.

[mparks8590]

hi

follow how 2 but be very careful of the black tabs that hold the fuel lines in. break those and you will need a new housing unit at £100 or more. ouch!

I use B&Q Boa constrictor for top part and halfords oil filter wrench to hold the bottom part then comes apart ok. make sure you tighten fully otherwise you'll get a fuel leak when re-pressurising

cheers

[Teapot]

UPDATE: I changed the fuel filter following the instructions on the howto, and made sure the housing was thoroughly clean and that the float-like thingey at the bottom of the housing was clean and moved freely.

Whilst I was in the engine bay, I also cleaned the boost sensor and removed the butterfly valve from the throttle housing as suggested in some other threads. I was suprised at the amount of gunge in the throttle housing and manifold, especially as it has done less than 25k since the egr valve and manifold/swirl valve assembly was replaced.

It runs noticably smoother at low revs (it used to judder very slightly during low-speed cruising) an the turbo seems to spool up quicker. When suddenly applying full throttle it also used to be like it would have a burst of acceleration, then hesitate for a fraction of a second, then continue accelerating. This problem has also gone now.

Unfortunately I still have a spanner light on cold starting, so I guess I'll have to take it for a reading when my favourite garage opens again in the new year.