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View Full Version : ECU cannot be reached



Stricken
25th April, 2020, 10:21 AM
Bought a Seat Leon Mk2 Cupra in March 2019, really low mileage car, verified and i really enjoy it.
The car has a stage1 made by a so called BMM Motorsport software reseller in my country. Car was mapped by the previous owner.

At the end of the year, i was helping a friend start up his car after his battery died so i hooked up some cables the proper way, tried to start his car, battery was so dead it wouldn't start.
I then decided it was time to quit and told him to buy a new battery. Took a look at my car while it was still running, the engine was shaking a lot, got into the car to shut it off i had a check engine light on. The car was running bad, like it was missfiring a lot.

Grabbed my VCDS and tried to look for the error and then discovered that i cannot read the engine whatsoever. I thought that it might have something with the car being turned off. Started the car, ran the scan again and the car started to go nuts. It went from normal RPM (750 RPM) to 0 and then back up, while something was clicking in the left side of the dashboard. It did so untill i canceled the scan or an error saying the engine cannot be reached popped up.

The thing is the car developed a small shake or stutter when idling and then after a few months had another missfire with a blinking check engine which then turned into a full check engine light. Took it on a platform to a specialised service, they couldn't figure it out because they cannot read the ECU.

Talked with the previous owner, gave me the phone number of the guy that mapped it, had a chat with him about the engine idling poorly sometimes and all he said was "coil packs or spark plugs" which i already replaced. He also tried to read the engine and couldn't. All we can see is when the engine is running, is pulling up different sensors, as the MAF, RPM, Lambda sensors and so on. At this point i did not trust the guy to let him try and figure it out or remap it.

I will upload a log from january, ignore the HVAC error, it was caused by a fuse, and also the front right beam was caused by a deceased module which has already been replaced.

Any thoughts on this ? I don't really wanna remap it since this stage one puts about 310 horsepower with no lift shift and boost by gear settings, which i really like.
Please Help.

speedy100
25th April, 2020, 12:43 PM
Hello,

It seems like things went crazy when Your friends car pulled all the juice out of Your battery... It is common problem with low voltage...
If You are lucky it is only a software problem. Disconnect the battery and leave it off all night. Connect next day and see if You communicate with Diagnostics...
If not You must reflash the ECU but in BDM mode.

Good luck

Stricken
25th April, 2020, 01:11 PM
I also thought of that but is unrelated. I did take the battery off, put it back on, the car works fine now. It did the same thing 3 weeks ago, i was waiting to talk with someone while i parked the car i stayed in the car while idling and a blinking check engine came on and the car started going nuts, missfiring, turned it off, left it there for like 1 hour. When i came back, started it, check engine light on, drove it home like that, took the battery off, 12 hours later i start the car, it does the same thing. Called a trailer, took it to a shop, when it reached there, started the car to take it off the trailer and it ran perfectly fine.

The shop failed to find a culprit since they could not read the ECU.

Yesterday went to a tuner and talked to him, he said somehow the can gateway is blocked and that it is fixable but not by OBD. Maybe they will take the ECU out and flash it in a different way .. i just thought that there might be a coding/fix that i could do myself, hence i searched google and found this forum.

Thank you for your reply

speedy100
25th April, 2020, 01:34 PM
Yes let them reflash it in BDM mode and if there is no hardware problem it will most probably be OK.

Best Regards