Spanner light...possibly glow plugs but op-com doesn't pick it up

[marky2027]

I've got the spanner light on the 2nd turn of the ignition. It started doing this last week when it was bitterly cold outside. i plugged op-com in and it only found the power steering fault I already knew existed. Cleared all fault codes and the spanner light went away. it has come back this morning but came on for about 30 seconds after about a mile of driving. Straight away I suspected glow plugs (already had a couple replaced). Plugged in op com but it didn't find any problems with engine ECU. Cleared all fault codes and the spanner light is off again.
So should op com find fault with the glow plugs? I tried a tell time and relay test but didn't get any results?
I haven't got a multimeter to test the plugs but my mate has so might try that. Any ideas? What about the glow plug relay? is this expensive? Car is 1.9 150 with 102k

[tony-1977]

If it's coming on AFTER a mile of driving, I wouldn't think glow plugs. It would stay on from a cold start, for about a mile, then go out.

Best take your laptop with you, and try read the codes when the light is on

[marky2027]

If it's coming on AFTER a mile of driving, I wouldn't think glow plugs. It would stay on from a cold start, for about a mile, then go out.

Best take your laptop with you, and try read the codes when the light is on

Last time it did this wasn't that proficient with the car and the stealers told me it was a glow plug fault and it got replaced under warranty. I'm sure if it comes on when driving and then goes off it's a tell tale sign of being a glow plug. I just thought op com would have picked something up