Quick spanner light question

[Sharks35]

So ive had a new engine recently put in my 2005 1.9cdti 120.

When i start the car the first time, the spanner light comes on and stays on.

if i turn off and start up again it goes out when strated and stays off.

If i start driving when its on and flick the ignition off and on again it goes off and stays off.

If the car is left for a few hours when i start it comes on and stays on until i turn the ignition off and on again.

Ive tried my code reader but nothing come up so need to find a tech2 one i guess.

Any ideas?

[SlowCoach]

You need to read when car spanner on dash appears. If you have ur own code reader or ccomputer reader, do it when it appears. As codes can delete if goes away.

[Critch]

One or more glow plugs faulty

easy check if you have a multimeter?