s2 aby will not start (vagcom only show g28 speed sensor fault)

[EvenM]

Hello

My s2 will not start and I only get the g28 speed sensor no signal fault with vagcom which I have read are normal when the car is not running during testing.


Backstory. I have for long time had problem with the car cutting with full throttle over 3k rpm, so I changed to tfsi coils, but the cutting was there still. So didnt sort that problem. Some weekends later the car wouldnt start, it was about - 10 degrees outside. The funny thing is that it started the next weekend in + 2 degrees, which can give a hint about that there is indeed a electric problem? The car have since refuse to start at any temperature.

I have read that the g28 sensor is not likely to fail, but in my case it could be the only fault when the testing does not find any more faults?

[Monkeymagic]

Have you checked for fuel and a healthy spark?

[EvenM]

Have you checked for fuel and a healthy spark?

No, will do tomorrow I have searched and read all the threads I could find here and I understand it could be one of the sensors or maybe the fuel pump. The fuel pump relay is okey, tested that in my other audi.

[UrS4boy]

Potential reasons why your AAN/ABY/ADU isn't starting:

Hello . Some weekends later the car wouldnt start, it was about - 10 degrees outside. The funny thing is that it started the next weekend in + 2 degrees, which can give a hint about that there is indeed a electric problem? The car have since refuse to start at any temperature.

IF the power in the battery is insufficient to spin the starter fast enough to get the engine to spin more than 13 RPM, the safety nanny inside the ECU will NOT fire the fuel pump relay (which in turn powers a bunch of stuff needed to start the car). Try on a warmer day with a fully charged battery and report back.

Potential reasons why your AAN/ABY/ADU isn't starting:

http://forums.quattroworld.com/s4s6/msgs/210191.phtml

[Cymru1]

Check power to fuel pump. Even though all fuses may seem to be perfect, check at the pump itself.

Easiest way. Wire up a direct feed to the pump from battery - bet she fire's up.

[EvenM]

IF the power in the battery is insufficient to spin the starter fast enough to get the engine to spin more than 13 RPM, the safety nanny inside the ECU will NOT fire the fuel pump relay (which in turn powers a bunch of stuff needed to start the car). Try on a warmer day with a fully charged battery and report back.

Potential reasons why your AAN/ABY/ADU isn't starting:

http://forums.quattroworld.com/s4s6/msgs/210191.phtml

Thanks, I have read all the threads I could find here and yours helped a lot

Started today with checking spark and fuel, nothing. So I took out the g28 speed sensor and it had some dirt on it. Cleaned it, put it back in, and the car fired - great success

[EvenM]

Check power to fuel pump. Even though all fuses may seem to be perfect, check at the pump itself.

Easiest way. Wire up a direct feed to the pump from battery - bet she fire's up.

Thanks, that would have been my next step if it was not the g28 sensor

[UrS4boy]

Thanks, I have read all the threads I could find here and yours helped a lot Started today with checking spark and fuel, nothing. So I took out the g28 speed sensor and it had some dirt on it. Cleaned it, put it back in, and the car fired - great success

I have read that the g28 sensor is not likely to fail, but in my case it could be the only fault when the testing does not find any more faults?

Hmm...an actual g28 code 2111 or DTC 00513Engine speed sender (G28) -Implausible signal -No signal that was real. Very rare. Good to know. It does happen.

What kind of "dirt"? Metal shavings? Oil?

BTW: This link has an excellent list of the Motronic ECU fault codes that we would be concerned about:

http://www.s2-audi.co.uk/tech_articles/motronic/ecu_faults.htm

[EvenM]

QUOTE=UrS4boy;888087]Hmm...an actual g28 code 2111 or DTC 00513Engine speed sender (G28) -Implausible signal -No signal that was real. Very rare. Good to know. It does happen.

What kind of "dirt"? Metal shavings? Oil?

Both, some metal on the tip of the sensor, and oil.

BTW: This link has an excellent list of the Motronic ECU fault codes that we would be concerned about:

http://www.s2-audi.co.uk/tech_articles/motronic/ecu_faults.htm

Thanks

[UrS4boy]

What kind of "dirt"? Metal shavings? Oil?

Both, some metal on the tip of the sensor, and oil.

You might want to keep an eye on the G28 then. The metal is coming from somewhere, e.g. the nose gear on the starter or the ring gear on the flywheel. It might return with time and cause the same problem. At least the next time, you will know right away what to do.

[betterwith4]

Back when my car wouldnt start and was cutting at full throttle i found it was my after market alarm ( clifford to be exact) that was put onto the car before i bought it i took that alarm off the car and its running fine after it cut out on the motorway and wouldnt give me any ignition at all ... funny thing was when i plug my scanner into the car g28 no signal came up but when i looked into it and cleaned it etc the fault code only disappeared when the engine was running because the sensor was receiving a signal from the engine running ( the sensor will not have signal of the engine isnt running to give it a signal i found) i dont know why this was but that was just a thing that occured to me... have you any other details ? Has the car got ignition? Have you done any mods eg uprated fuel pump / serviced it maybe wrong spark plugs fitted? Reason i ask this is because these may not show as a fault code

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[UrS4boy]

If you pull the fault codes with the engine off you will ALWAYS get a G28 fault code. ALWAYS

[betterwith4]

If you pull the fault codes with the engine off you will ALWAYS get a G28 fault code. ALWAYS

I thought this also ... im sure you helped me with this similar problem when i eventually found out it was my alarm box had fried itself?? Do you recall?? 😂

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[EvenM]

You might want to keep an eye on the G28 then. The metal is coming from somewhere, e.g. the nose gear on the starter or the ring gear on the flywheel. It might return with time and cause the same problem. At least the next time, you will know right away what to do.

Yes, I have to keep that in mind

[EvenM]

Thanks for good tips

I also thought it could be the fuel pump, but it started after I cleaned the G28 sensor.

My next problem is fuel / boost cut out with full throttle.Thought it was the org coils who started to fail but it was not Can be a leak somewhere but have not found any. Does not have any faults with vagcom.My car does not have any alarm.

Back when my car wouldnt start and was cutting at full throttle i found it was my after market alarm ( clifford to be exact) that was put onto the car before i bought it i took that alarm off the car and its running fine after it cut out on the motorway and wouldnt give me any ignition at all ... funny thing was when i plug my scanner into the car g28 no signal came up but when i looked into it and cleaned it etc the fault code only disappeared when the engine was running because the sensor was receiving a signal from the engine running ( the sensor will not have signal of the engine isnt running to give it a signal i found) i dont know why this was but that was just a thing that occured to me... have you any other details ? Has the car got ignition? Have you done any mods eg uprated fuel pump / serviced it maybe wrong spark plugs fitted? Reason i ask this is because these may not show as a fault code

Sent from my SM-G925F using Tapatalk