Car starts and shuts down immediately

[HempEyn]

Hi.

I am new here (just registered). I have a problem with my Seat that has been going on for few weeks now and I am out of ideas of what might be the cause to the problem. The car starts normally but then shuts off right after, I have checked it with vag-com and I had the 17978 fault code. Additionally it said short to B+. I clear the code and car starts fine, sometimes it starts fine without doing anything. On top of that, today I could not connect to the engine, I could scan the ABS and internal conv I think it was. Please help me as I have lost my hope.

I drive a Seat Leon Mk 1 2000 1.6.

Thanks in advance

P.S The immobiliser icon is not flashing.

 

[Muttley]

The fault code and the symptoms both point to the immobiliser. It can be hard to diagnose such faults. It could be the read coil, which fits around the ignition lock - it will be worth checking the connector between this and the instrument panel. If the coil or its connection is flaky, this will result in the immobiliser check failing, and causing the symptoms you see.

If you have another key, check to see if you experience the same symptoms with it. If so it would confirm the car-side immobiliser system is faulty - if not then it is the transponder chip in your key (but I've not seen one of those behave intermittently, any failure is usually complete)

Otherwise it could be the coil itself, or in the worst case, the immobiliser module.

 

[HempEyn]

Thanks Muttley for such a fast response. I don't have a spare key therefore I can not eliminate that the key might be faulty however it is mind blowing that it behaves intermittently. One thing I forgot to mention is that I had a problem with the RPM, it was going crazy all the time, usually between 1000 and 1300 so I blamed the throttle body. I replaced it but the symptoms persisted so I put the old throttle body back on, and then the next day the car started having the problem where it would just cut off immediately, I disconnected the battery and reconnected it again after about 30 sec and the car started. Tried it few times and it worked but then again, just cuts off. Since then I have been struggling with this and it is just a nightmare.

P.S the problem with RPM was the power steering oil pressure switch.

 

[SlimsLCR]

I'm not 100% sure but if you disconnect the throttle body, you need to reset it again via vagcom, I know this is the case on my lcr, your engine may be different! Sounds like an immobiliser problem too me too, I'm not big on auto electric stuff but defo check out the throttle body to see if it needs reset! You didn't drop your key or give it a thump of anything recently?

 

[HempEyn]

I don't think the throttle body needs resetting because when the car starts it runs perfectly. It is annoying that the issue with starting the engine isn't there all the time. I thought it might be the immobiliser too but how come it's showing it doesn't get enough power? How come the orange immobiliser light isn't flashing? How come it does it intermittently?

 

[SlimsLCR]

The symptoms point towards the immobiliser, but when you have an engine dependant on a computer and sensors to make it work it could be anything! On an old Volvo I had I had problems with it doing the same thing, it would start and stop and mess about, turned out to be a faulty earth wire! But i doubt that is the problem here! You might need to take it to an auto electric shop to have it looked at!

 

[HempEyn]

This morning I started to hear a strong ticking sound, the kind of thing you get from a spark plug. It was coming from where all the relays are located. I disconnected the 409 relay and the sound stopped. I think this may be faulty and may bot be supplying enough power to the ecu and immobiliser so I sent someone to the shop to get a new one. I'll update when I replace it.

 

[HempEyn]

I replaced the 409 relay but it's just the same. Why is there a ticking sound in it? Never did it before

 

[pedro1989]

I'm pretty sure the 409 is the fuel pump relay - that being naff would prob give your symptoms.

Maybe it's priming but then not clicking over to permanent when it starts and then it dies (much like the immobiliser issue)?

 

[HempEyn]

The fuel pump and relay works but it looks like it isn't getting enough power just like the immobiliser so it must be an electrical issue.

 

[HempEyn]

I guess no one has a clue of what's going on with it. It definitely looks like an electrical issue to me so I will try to pursue that. One more thing tho, while looking at the relays I didn't notice a 109 relay but there is clearly a space for it anf wires going into it just like to the others. I'm sure it wasn't there when I bought the car and it was running fine but maybe someone by passed it and now it's messing everything up? Any thoughts?

 

[MoToJoJo]

Relay 109 is for diesels only, does the same job (ish) as the 409 relay in a petrol.

Google is your friend as this appears to be common in Golfs

http://www.honestjohn.co.uk/forum/post/?t=82699

 

[HempEyn]

It turnes out it was a faulty crankshaft sensor. Replaced it today and so far the car starts and runs perfectly.

 

[HempEyn]

So... It started raining during the night and the car wouldn't start in the morning. Why, you ask. I'm not 100% sure but it looks like seat did a really **** work installing the ecu just under the wiper unit. I took it out and it turned out that the ecu and all connections are soaked. The rubber on the bottom of the ecu is really bad and it looks like it's letting water in or simply moisture. I'm drying the ecu along with the connections and should test it tomorrow.

Well done Seat!

Sent from my SM-N9005 using Tapatalk

 

[Shabobchik]

I agree great place to sit an ECU...

I've been trying to sort mine for a year... done everything. DOORS, The 140mps push thing, dash out cleaned pins, punching the dash.... A LOT. I was ready to jack it in, then yesterday i went at the ecu.

one of the water runners was loose running water onto the ecu, and the drainage hole below it on drivers side was blocked causing the thing to fill with water. I've cleaned it all up and cleared hole and today it started. Now unless it's a christmas miracle i'm claiming a win. It's raining hard today so if it runs tomorrow i'll report back but if anyone is having the immobiliser fault and your carpets are dry i would look here.

take windscreen wipers off, pull the plastic trim off and rubber seal - careful there a wire attached. Look in the driver side you'll see the hole or leaves and mud in my case.

Hope this helps someone.