Engine firing up but dying immediately

Question

The car in question is a ~15year old Opel Corsa C: The engine starts immediately, without any problems. After 2-5 seconds of running the engine just cuts off. There is a blinking CEL, but my reader claims there are no trouble codes set.

Performed checks / noticed symptoms:

• The fuel pump seems to be running, as I hear it. At the moment I do not have the means to measure the fuel pressure.
• As a test I detached the air intake pipe from the throttle body, nothing changed.
• I could observe the throttle valve moving. I cannot tell if the movement is consistent with normal behavior.
• I could not check the spark plugs yet. I suspect that they won't be faulty as the engine is clearly running after startup.
• After the starting attempts there is a smell of fuel present in the air. I could not detect any visual leaks.
• Pressing the accelerator does not prevent the cut-off.
• Despite not pressing the accelerator, immediately after starting I could observe the RPM to rise to 2K when the engine cut off.

Some observations about the car:

• One oxygen sensor got replaced a year ago.
• The car was sitting for 10 days in the garage, so I want to exclude cable damages by martens.
• The fuel filter was never replaced, as the car has only ~50KKM it won't be my primary suspect.
• There were no repairs or other meddling with the engine in the last year.
• There are no visible damages to cables, engine or other things.

Could somebody suggest me other checks to perform (Besides getting a better code reader)?

Edit:

The blinking CEL, according to the user manual, is the indicator for an engaged immobilizer. Switching keys did help. It was helpful to detach the battery temporarily, the engine started afterwards. It is however no permanent fix as a second start still results in the immobilizer deactivating the engine.

Answer 1

There are a few known problems with the Corsa C

Firstly the coil pack can suddenly fail without much warning (although as you mentioned it probably isn't this)

The Engine ECU is poorly designed resulting in components inside becoming disconnected, the most common fault is loss of 5v to a certain group of sensors. To check this check that you have 5v at sensors such as throttle position sensor, accelerator sensor, MAP/MAF etc etc. As your engine is revving by itself it sounds like it could be a ECU fault. If it is only faulty bonds inside, these can be repaired by specialist companies.

The plastic inlet manifold can crack behind and below the throttle body or around the EGR inlet if fitted or wiring/pipework can rub through it. This will suck in unwanted air and cause the engine to rev the ecu will then detect this and cut it due to safety. To check this there are a number of ways firstly visually and by feel and you can remove the throttle body to get a view from inside. Ideally you need a smoke machine which emits a non toxic and non sticky smoke under pressure but if you don't have access to one you can VERY carefully pressurise the intake manifold with compressed air and listen for hisses.

The immobiliser system can become faulty but this doesn't normally cause the engine revving by itself but still cannot be ruled out. Ideally you need a better code reader with live data to see if the ecu is locked so if you don't have that you would need to send the ecu, keys and immobiliser ecu off to a ecu testing/repair company.

These faults will allow the engine to run for a few seconds. You really can't do much more without live data

Answer 2

It turns out that replacing the battery was enough to cure this ailment.

Cargo cult treatment at is finest...

Perhaps the internal resistance (original battery) was high enough to cause electrical disturbances, but still low enough to crank the engine.