G71 Error: Troubleshooting & Solutions

Hello, back after the winter break. Here's the problem.
I've now installed an AFN engine in my Golf 3. The engine is running, but it's not building any boost, and the engine control unit (ECU) is showing an error code G71... something.
That means the pressure sensor is probably broken. Is that possible? Or could it be something else? It also has trouble starting. Could that also be related to the boost pressure? The injection timing was just adjusted by VW recently.

Hello,

Please provide the error number instead of just saying "G71 something..."
Furthermore, the model year and mileage would be interesting to know.

I didn't write them down, unfortunately. And, unfortunately, my own laptop only has a USB port.
The engine is from a 2000 Sharan (AFN). The engine control unit (ECU) is from a Passat AFN.
I did a little improvising. Is it possible for the pressure sensor to break, or will an error be displayed if the boost pressure doesn't build up and deviates from the expected range?

G71 ist ...Unplausibles Signal Saugrohrdruck. Sure, here's the translation:

'O.ä.' translates to 'etc.' or 'and similar' in English.

The sensor G71 is located in the control unit and is actuated by a small hose that comes from the coolant system.
Check if you've connected the hose directly from the LLK pipes to the STG.

There are several possible causes for the error, but I would start by checking the 'vacuum hose.'

arne


p.s. - please correct me if I am wrong

Thanks for the tip, Arne. Unfortunately, that wasn't the problem. Could you list a few more possibilities? I'll check everything thoroughly. Does the error also appear if the VTG (Variable Turbine Geometry) isn't working correctly and the pressure deviates from the expected values?

Okay, so the hose is absolutely leak-proof, undamaged, and not blocked, right?

'This sensor is located in the control unit, and a pressure hose runs to it... the other end of the hose is connected to the lower radiator pipe. Check there to see if everything is okay and not blocked. You might want to blow through the small hose and definitely check for leaks.'

You can also thoroughly inspect the entire lubrication system for leaks, which may be noticeable as a small oil seepage.

To my knowledge, this sensor doesn't have much more to it. Of course, it could also indicate an error in the sensor if the problem lies elsewhere.

Good luck.
arne

Hi Arne. I've now removed the pressure hose and blown it out with a compressor. About 8 liters of oil came out. No, not that much. But initially, there was good pressure in the hose, and then a fountain of oil came out - so now I'm also covered in oil. What about the pressure sensor in the control unit? Can that be cleaned, or does it not matter if there's oil on it?

I tested the turn signal VTG (Variable Torque Generator) and it's working. However, the torque converter isn't receiving power from the control unit (ECU). Could this be due to a potential limp-home mode, and would it resolve itself after cleaning the hose, or is it a different problem?