# ESP Fault Longitudinal Acceleration Sensor G251



## jonpl (Apr 25, 2014)

I have a Mk2 (8J) Audi TT 3.2 Quattro, and I've struggled to find similar posts for the Mk2 (there seemed to be plenty for the Mk1). Here goes:

I have an intermittent ESP fault. Running in through VAG gives me the following:

```
Address 03: ABS Brakes        Labels: 8J0-614-517.lbl
   Part No SW: 8J0 614 517     HW: 8J0 614 517 
   Component: ESP MK60E1          0130  
   Revision: 00H52001    
   Coding: 0017985
   Shop #: WSC 01236 785 00200
   VCID: EAD1330CC56476E

1 Fault Found:
01279 - Longitudinal Acceleration Sensor (G251) 
            008 - Implausible Signal
             Freeze Frame:
                    Fault Status: 01101000
                    Fault Priority: 2
                    Fault Frequency: 38
                    Reset counter: 91
                    Mileage: 32219 km
                    Time Indication: 0
                    Date: 2014.02.06
                    Time: 17:40:19

             Freeze Frame:
                    Count: 14592
                    Count: 8193
                    Count: 210
                    Count: 48384
```
Looking at the service manual (ETKA) it seems to say the Longitudinal Sensor is located right behind the bonnet catch (see attached image)










Here's a photo










I replaced the sensor, but the fault still persists. I found a post on this forum about measuring the sensor output (see picture below), although I'm not convinced I am looking at the right sensor. My fault code is for the G251 sensor, but I can only find the measuring blocks for the G200 sensor (Lateral Acceleration Sensor). Are those one in the same?










The value of the G200 sensor seemed to be within tolerance. Any help / pointers / suggestions welcome.


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## jonpl (Apr 25, 2014)

Any suggestions anyone?


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## TT-driver (Sep 14, 2010)

See for a bit more info here:

http://www.volkspage.net/technik/ssp/ssp/SSP_381.pdf


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## bobbobb (Dec 24, 2008)

thats the front airbag crash sensor, this is the code it brings up in vagcom

01738 - Crash Sensor for Front Airbag; (G2830) part number is 8j0959651

also that part number is the abs control unit but this might help

01279
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Contents [hide] 
1 01279 - Longitudinal Acceleration Sensor (G251) 
1.1 01279 - Longitudinal Acceleration Sensor (G251): Implausible Signal 
1.1.1 Possible Symptoms
1.1.2 Possible Causes
1.1.3 Possible Solutions
1.2 01279 - Longitudinal Acceleration Sensor (G251): No or Incorrect Basic Setting / Adaptation 
1.2.1 Possible Causes
1.2.2 Possible Solutions

01279 - Longitudinal Acceleration Sensor (G251) 
01279 - Longitudinal Acceleration Sensor (G251): Implausible Signal 
Possible Symptoms 
Malfunction Indicator Lamp (MIL) active 
Possible Causes 
Longitudinal Acceleration Sensor (G251) Calibration not performed 
Wiring/Connectors from/to Longitudinal Acceleration Sensor (G251) faulty 
Possible Solutions 
Check Longitudinal Acceleration Sensor (G251) 
Use Measuring Value Blocks (MVB) to check Sensor Signal for plausibility 
Check Installation Position of Longitudinal Acceleration Sensor (G251) 
Perform Longitudinal Acceleration Sensor (G251) Calibration 
See Vehicle specific Diagnostic Procedures 
Check Wiring/Connectors from/to Longitudinal Acceleration Sensor (G251)


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## jonpl (Apr 25, 2014)

Thanks for the replies - the "Service Training" manual says that G419 unit contains the sensors I'm interested in:


> *Sensor unit G419* The sensor unit comprises senders G200 (lateral acceleration sender), G202 (yaw rate sender) and, on models with quattro four-wheel drive, G251 (longitu-dinal acceleration sender) . The sensor unit has been adopted from the Audi A3. The service procedures for calibrating the sensors are the same as for the Audi A3.


The following link seems to suggest it's located in the 'centre tunnel' (near the gear lever) - I assume near the main Airbag Unit. I'll remove all the trim and report back with my findings

http://www.audi-portal.com/en/diagnosti ... 17411.html


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## TT-driver (Sep 14, 2010)

Do you have access to vagcom and did you try calibrating the sensor? Sensors like these don't have a habit of failing as far as I'm aware.


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## jonpl (Apr 25, 2014)

A colleague of mine has Vag Com but the 'Login' button was not enabled (as described in viewtopic.php?f=2&t=153716). Not sure whether we had the right cable. We could measure everything ... and certainly everything seemed to be within tolerance when driving and at a standstill - so I didn't think a callibration would fix this fault. It's as though there was an intermittent 'blip' every now and again. I took the box apart and noticed the soldering was questionable around the socket pins - which I quickly remedied ... but still no joy :?

So I opted for purchasing a 2nd hand unit off eBay. So far driven 500 miles and everything seems to be ok (usually it would fail after less than 5 miles).

Just for peoples reference in case they need to replace this sensor on a Mk2 8J TT ... I've attached a photo of the black box:










Thanks for the replies helping me to find the sensor. So far so good ... now my window regulator decided to pack-in leaving the window half way down ... so off to fix that now


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