That should be the immobilizer but you say there's no flashing light.
I found this list by MOGOlf of possible causes of a flashing glow plug light:
00741 Brake pedal monitoring - implausible signal (brake pedal switch)
01044 Control unit incorrectly coded
16705/P0321 Engine speed sensor - implausible signal
16706/P0322 Engine speed sensor - no signal
16955/P0571 Brake light switch (F) - implausible signal
17653/P1245 Needle lift sender (G80) - short to earth
17654/P1246 Needle lift sender (G80) - Implausible signal
17655/P1247 Needle lift sender (G80) - Open circuit/short to positive
17762/P1354 Modulating piston movement sender (G149) - electrical fault in current circuit
17969/P1561 Metering adjuster (N146) - control difference
17978/P1570 Engine control unit blocked
18020/P1612 Control unit incorrectly coded
18026/P1618 Glow plug relay (J52) - short to positive
18027/P1619 Glow plug relay (J52) - open circuit/short to earth
18040/P1632 Accelerator position sender - voltage supply
Did this happen after a battery change or jump start?
Before you do any thing else try disconnecting the battery cables and touching them together for a minute or so. This will dicharge all computers and capacitors in the entire car and reset all adaption and radio to base settings. You will neeed your radio code too.
Be aware that all learned or adaptive values will need to relearn, the car may run slightly different until it figures stuff out again, but it will learn it's way back to normal.
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