I have a 2012 Skoda Octavia TDI (1.6L CAYC diesel 77kw, Auto 7 Gear DSG) with an issue I can’t figure out…

 

Yesterday I was driving for an hour and everything was seemingly fine, aside from the engine being a little powerless which I only associate with the turbo and DPF being a bit clogged up with soot.

 

I parked the car for an hour when I got home but when I started it again the glow plug light flashed, and the car went into limp mode…. (I have had that issue with other cars but after restarting the cars it would usually clear and I would be able to get home…not in this case). The car would not comply to any input to the accelerator and after 2 minutes the engine died on me. It turns over but doesn’t want to start, just flashes CE light and coil light.

I was able tow the car to a friend’s garage where I lot of speculations are going on but no solutions.

-All the fuses are good

-All the relays have been checked.

-The ECU doesn’t seem to be getting any power (I measured the connector going to it)

-The ECU is getting ground.

-The coil light does not appear in the dashboard when trying to start

 

Any help would be so great as this is the family car and I can’t stay for very long without it.

 

14 minutes ago, Ingo1392 said:

lot of speculations are going on but no solutions

He doesn't seem to have read the fault codes, so is reduced to guesses and/or using the parts cannon.

4 minutes ago, KenONeill said:

He doesn't seem to have read the fault codes, so is reduced to guesses and/or using the parts cannon.

It is not possible to read the fault codes as the ECU is not getting power and not showing on the OBD reader.

Double check cabin fusebox fuse 1 (10A), and under-bonnet fuses 10 (5A) and 13 (30A).

Which pin/pins at the ECU connector did you find lack of power at?

Edited 20 September, 20223 yr by Breezy_Pete

2 hours ago, Breezy_Pete said:

Double check cabin fusebox fuse 1 (10A), and under-bonnet fuses 10 (5A) and 13 (30A).

Which pin/pins at the ECU connector did you find lack of power at?

I triple checked all the fuses, and relays. 

 

There are three pins that are supposed to provide power (I don't remember the number on the pins), and none were providing power.

 

I am wondering if aside from fuses and relays what could cause a lack of power to the ECU? apart from a broken wire for example. I am trying to see where in this chain of events something like this could occur.

There are more than this, and most of those will only be powered under certain conditions.

 

The only one that you should always see 12V at is pin 92. This feed should also be found at the connection '85' for relay no. 1 in the e-box.

 

All the other feeds are dependent on ignition switch position and other factors. 

 

The feed from cabin fuse 1 to pin 87 of engine ECU should only be powered when ignition is on.

 

The connection between ECU pin 69 and terminal '86' of the relay no. 1 must be pulled to ground/0V by the ECU to energise the main relay (no.1) which then feeds power to pins 3, 5  and 6 via fuse 13, which I expect are the ones you have probed?

 

 

Edited 20 September, 20223 yr by Breezy_Pete

On 20/09/2022 at 12:56, Breezy_Pete said:

There are more than this, and most of those will only be powered under certain conditions.

 

The only one that you should always see 12V at is pin 92. This feed should also be found at the connection '85' for relay no. 1 in the e-box.

 

All the other feeds are dependent on ignition switch position and other factors. 

 

The feed from cabin fuse 1 to pin 87 of engine ECU should only be powered when ignition is on.

 

The connection between ECU pin 69 and terminal '86' of the relay no. 1 must be pulled to ground/0V by the ECU to energise the main relay (no.1) which then feeds power to pins 3, 5  and 6 via fuse 13, which I expect are the ones you have probed?

 

 

Thank you for your reply.

 

I am further away from figuring out what is wrong than initially.

 

I somehow got the ECU to respond and was able to get a read on it through OBD. Lots of Errors cleared them and after some fiddling the car started....

 

While holding the ECU I tilted it slightly and the engine started to run roughly, when I tilted it back it went back to normal. This happened a few times and then stopped, no matter how much a shook the ECU the car ran fine no errors.. nothing. So my initial thought was that there must have been some corrosion on the ECU connector that was able to go away enough after a few tilts for everything to be good.

The day after I was all excited about putting everything back together but... lo and behold.. the car wouldn't start. Back to square one.

I am not sure if it can be related but the wires in the wiring loom going to the drivers side door were bare of their insulation and some were toughing and some were green from corrosion as well the plug going to the body making it not possible to open or close any window on that control panel.

 

I am pulling my hair out from frustration at this point and I hope you have some insight in what could be the cause of this dreadful headache.

58 minutes ago, Ingo1392 said:

Lots of Errors

Did you make notes of what the errors were?

No, I did not. It just seemed as if the ECU was on the fritz so I did not really trust any of these codes.

 

intermittently the cooling fan would turn on max when the ignition was on for no apparent reason.

9 minutes ago, Ingo1392 said:

intermittently the cooling fan would turn on max when the ignition was on for no apparent reason

 

I believe I have read reports of that being fixed by replacing the main ECU relay (#1 in e-box).  You said in your first post that the relays had been checked, but I think it would be good to try another relay in that position.  Is there another with the same number on the top of it that you could swap from another position?

 

Thank you for all your help, I finally found the issue. I decided to open the ECU and what do you know... It was full of water. Bought a used one on Ebay for about 100£ and payed a certified VW repair shop 250£ to program everything back together and it runs as it should now aside from low power at low rpm and occasional coil light flashing with no limp mode. So I will be checking the EGR and the turbo vanes next.

42 minutes ago, Ingo1392 said:

I decided to open the ECU and what do you know... It was full of water.

 

That's not ideal. 

14 minutes ago, Breezy_Pete said:

 

That's not ideal. 

haha, no I was sure it wasn't one of those watercooled circuit boards. But glad It was only this. The dealership quoted 1650£ for a new ECU so I was glad to find it used on ebay.