Pressure Sensor for Brake Boost (G294): Implausible Signal Fault

chumsofmanutd

chumsofmanutd

A2OC Donor
Hi,

the other day when I was driving a long all of a sudden the car went into limp mode and the brake lights started madly flashing and beeping at me. I got home and scanned the car and found the fault:

18322 - Pressure Sensor for Brake Boost (G294): Implausible Signal

After that, I cleared the fault and the car was perfectly fine! I've been out in the car for quite a while and had no problems at all. I checked on Ross Techs site for causes - it suggest's checking the fuse, connector and the g294 boost pressure sensor. I've looked on ElsaWin for the mentioned sensor but cannot find any reference to it. I've found the brake pressure senders underneath the reservoir (G201 & G214) but no reference to G294. Has any one any idea whether this sensor exists and if so where it is located as I would like to check it.

The car is the 1.6 FSI by the way.

Cheers Rob.
 
spike said:
The attached link is not A2 specific but page 43 gives some info on the function and location of the G294 sensor. The A2 location must be similar - either on the brake servo or in the pipe from the intake manifold to the servo
http://www.scribd.com/doc/49513807/110106-VW-1-4L-TSI-Engine-SSP-359

Cheers Spike
Click to expand...

Thanks Spike, that's interesting. It seems unusual that I can't find any reference to it on a A2 engine though. Anyway, so far it has not caused a problem again (touch wood) so I'm hoping it was a one-off and am going to leave looking into it for now.

Cheers Rob.
 
hi chumsofmanutd

i wanted to ask if you found a solution for 18322 - Pressure Sensor for Brake Boost (G294): Implausible Signal error code you got as i am getting the same with some misfire codes aswell.
 
The schematic shows it as:
"Brake Servo Pressure Sensor"
I'd expect it to be on the brake servo, or very close to it. It's has 3 connections to it.
Mac.
 
PlasticMac said:
The schematic shows it as:
"Brake Servo Pressure Sensor"
I'd expect it to be on the brake servo, or very close to it. It's has 3 connections to it.
Mac.
Click to expand...
May be a hint, this is where it is on an A4:
pic03.jpg


Mac.
 
Well IF one is fitted it is incorporated into another unit perhaps the servo itself? Or is it only fitted to the larger LHD brake servos?

Certainly no mention of a G294 in either the MK20 or MK60 ABS systems.
 
Yes there are pressure sensors on the brake lines on the master cylinder but they are hydraulic pressure sensors, not a vacuum boost sensor.
 
Just to clarify a little. The wiring diagram Mac has posted above is in a section for the FSI BAD code engine. Of the three wires shown connecting the G294, one is to the ECU shown, the other two via welds are connected to the NOx Sensor Control Unit by the diagram paths 'a' and 'b' extensions to the next diagram, physically in the passenger footwell.

All rather mysterious.

Andy
 
Andrew said:
Just to clarify a little. The wiring diagram Mac has posted above is in a section for the FSI BAD code engine. Of the three wires shown connecting the G294, one is to the ECU shown, the other two via welds are connected to the NOx Sensor Control Unit by the diagram paths 'a' and 'b' extensions to the next diagram, physically in the passenger footwell.

All rather mysterious.

Andy
Click to expand...
Andy, Do you think it is only fitted (if it is) to the FSI?
It could be that it's not fitted anywhere, but the ECU has provision for it, which has not been mapped out correctly.
Mac.
 
PlasticMac said:
Andy, Do you think it is only fitted (if it is) to the FSI?
It could be that it's not fitted anywhere, but the ECU has provision for it, which has not been mapped out correctly.
Mac.
Click to expand...
I have checked the schematics for the 1.4 Petrol, and there is no G294. So it's an FSI mystery (one of many).
Mac.
 
PlasticMac said:
Andy, Do you think it is only fitted (if it is) to the FSI?
It could be that it's not fitted anywhere, but the ECU has provision for it, which has not been mapped out correctly.
Mac.
Click to expand...
I don't know but the evidence points that way.

An initial peruse of forum posts including G294 over the years are all from FSI owners.

The wiring diagram shows you posted is identified as No 41/6, the start of section 41 clearly identifies it as relevant to the BAD engine code - For Model year 2004 and the only other place G294 pops up is section 3 which is the same for Model year 2003, at least in my copy of the wiring diagram.

Andy
 
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