Polo 6N2 Engine start blocked by Immobilizer

[John24]

Hey guys,

Took my car to get new tyres and when I tried to start the key it would not. After 6 attempts it did. Got back and scanned with VCDS and saw this

Address 01: Engine        Labels: None
   Part No: 030 906 032 BC
   Component: ME7.5.10            3174  
   Coding: 00031
   Shop #: WSC 00000  
   VCID: 4C97934A7C7D9F2A79-5140

1 Fault Found:
17978 - Engine Start Blocked by Immobilizer 
            P1570 - 35-10 -  - Intermittent
Readiness: 0000 0000

Address 25: Immobilizer        Labels: 6X0-953-257.lbl
   Part No: 6X0 953 257 
   Component: IMMO                0004  
   Coding: 00001
   Shop #: WSC 00464  
   VCID: 7DF10E8E7747E6A2BE-4B02
   WVWZZZ6NZYY580027     VWZ1Z0Y0291758

1 Fault Found:
01176 - Key 
            07-10 - Signal too Low - Intermittent

Cleared the codes and tried again and it would sometimes start on the 5th go and sometimes. But no codes have come back. I looked at the readings and got the following with key in the and with ignition on.



When I turn the key to the ignition position I can hear the pump is not priming, but sometimes it does (seems random). I've tried a spare key and got the same result.

Any suggestions?
Thanks

[Keithuk]

VAG Error Code: 01176

Fault Location:
Key - Unauthorized - Signal too Low

Possible Cause:
Malfunction Indicator Lamp (MIL)(K83) active.

Immobilizer:
Wiring and/or Connector(s) from/to Immobilizer Reader Coil faulty.
Immobilizer Reader Coil faulty.
Immobilizer Transponder in Key faulty OR incorrect Transponder in Key.
Remote Control
Remote Control Battery low.
Remote Control faulty OR incorrect Remote Control used.

Possible Solutions:
Immobilizer:
Check Wiring and/or Connector(s) from/to Immobilizer Reader Coil.
Check Key Immobilizer Transponder Status.
Read Measuring Value Blocks (MVB).
Check/Renew Immobilizer Key Matching.

Check/Replace Key.
Remote Control:
Check/Replace Remote Control Battery.
Check/Replace Remote Control.

Special Notes:
If found on a New Beetle, can be caused by the Insulation Displacement Crimp (IDC) terminals that are used for the reader coil at T32a/2 and T32a/17 (green connector) that result in poor contact. This can degrade the signal from the key.
This Fault Code can be stored in due to Remote Control or Immobilizer Problems. On most Models these systems are separate and should therefor also be diagnosed separately.
In case of Engine Starting Issues please make sure that you are really experiencing an Immobilizer related Problem! On most models using conventional keys, the Engine will still start but cut out after 1-3 Seconds if an Immobilizer related Problem is the cause. On models using Kessy Systems and Electronic Keys, most systems in the car won't power up at all if its an Immobilizer related Problem is the cause. If you are NOT experiencing this behaviour (e.g. Instrument Cluster powers up, and engine cranks but doesn't fire at all or engine won't crank) this is likely NOT Immobilizer related.
When found in Audi A3 (8L), Audi A4 (8D), Audi A6 (4B) or Audi A8 (4D), check Wiring from Immobilizer Control Module to Immobilizer Reader Coil. A known issue would be the Length of the Wiring, an optimized Replacement Part may be available (8D0-972-275).
May be stored in Combination with 17978/P1570/005488 - Engine Start Blocked by Immobilizer in Engine Control Module.

As taken from my new EOBD II II Fault Codes Software

[John24]

Thanks for the reply Keith. It says Check Key Immobilizer Transponder Status and you can see the status is at 0, would that mean an issue with the key? If so wouldn't be odd that the spare key has the same issue?

[Keithuk]

It says Check Key Immobilizer Transponder Status and you can see the status is at 0, would that mean an issue with the key?

Check Key Immobilizer Transponder Status. That's this forum adding web links to certain words you just ignore those.

[John24]

Well I found a VCDS link that explains all the key outputs http://www.ross-tech.com/vag-com/car...ng-blocks.html Transponder Status at 0 means that my keys are no locked and can be reprogrammed for another vehicle.
I checked the coil ring around the barrel but all seems fine. I'm not too sure what's the best way to diagnose which part is causing the problem.

[Pete1]

If it's like the 9N Polo and brand sisters, the solder joints of the connector in the instrument cluster can give trouble, and on those cars the immo connections are right at the top end of the 32-way connector in question. The loom weight therefore tends to pull on those if there's any vibration, and crack the joints. I don't have 6N2 wiring info unfortunately, or I'd check to see if the arrangement was anything similar in a 6N2, but I wouldn't be surprised. Here's a little how-to from another forum, bookmark it quick in case it gets deleted: https://www.briskoda.net/forums/topi...tion-included/

[John24]

Thanks Pete1 I wouldn't even have thought that the instrument cluster could cause such an issue. As far as I am aware the 6n2 doesn't have an immobiliser indicator on the cluster but I will inspect it none the less.

[Pete1]

A quick google found this: https://www.clubgti.com/forums/index...pinout.282717/
Which suggests (if your car is younger than that 05.99 date) pin 2 and 17 are the immo coil connections, so almost the same as the 9N.
Worth a look if it's not too hard to get to the point you can eyeball the relevant solder joints.

[John24]

Once again thanks for the useful reply Pete1. Another thing I have noticed is that now the fuel pump is not priming on ignition. Looking at videos and posts seems that VW do prime the pump even when the immobiliser is on and can even allow the car to start for 2 seconds before the engine is cut.
After seeing the codes I believe the issue is with the immobiliser but since clearing the codes and trying to start the car multiple times they have not come back. I wonder if something else might have gone wrong. I will check if the current is being supplied to the fuel pump as well.

[John24]

Ok I have tested all the fuses all seem great but what I also tested was the spark on all 4 spark plugs there was none. So there is no spark being sent to the spark plugs it seems.

https://workshop-manuals.com/volkswagen/polo-mk3/power_unit/simos_injection_and_ignition_system/ignition_system_glow_plug_system/servicing_ignition_system/checking_ignition_transformer/

I also tested the coil pack secondary coils and got 4.7 koms which seems within spec and I also tested the output terminal which sending 12.8v to the coil pack. BUT when cranking the engine it was sending signal to terminals 1 and 3 which means the ECU was sending a signal to the coil pack if I am right. The testing manual says to use an LED i just checked if voltage was coming back at 1+4 and 3+4 pins which it was.