Hi guys,

I have what sounds like a boost leak. I am getting the error code P3802 Turbochargerboost sensor "A" circuit high Upperlimit value exceeded.

I have re-seated all boost hoses and Y Pipe, but it is still there.

Does anyone know which is sensor A? I am hoping it may help me identify the fault.

 

Hi,
I think you mistyped the code. The code should be P0238 IMO. You get this when the boost pressure sensor signal is above the predicted range.

Possible causes:
- Boost pressure sensor harness is open or shorted
- Boost pressure sensor circuit poor electrical connection
- Faulty boost pressure sensor
- Faulty Turbo/Super Charger
- Engine over temperature
- Ignition misfire exceeds the calibrated threshold
- Faulty Knock sensor (KS)

Hope this helps.

 

I definitely have the right code. Screen shot attached.

There is a very distinct boost leak sound.

 

Well I am probably wrong then. Is it durametric you're using?

Does your car misfire at all? Especially at idle.

 

Yes it is Durametric.

The idle drops a bit low after decal, maybe 100rpm. Otherwise it drives OK. It leaks boost when it gets to 15psi, and is down on power.

After I pulled it apart and put it together, it drove fine with no leak for a few boosts, before returning.

Can a faulty boost sensor cause it to vent boost?

 

I don't have anything helpful to add, but I can commiserate. That surge of hope when things seem to be working makes the letdown when they revert all the more bitter. Best of luck!

 

Thanks for your help. It maybe one for Porsche.

 

Have a look at your MAF sensors also. They might be getting a wrong signal. When there's a leak you often hear the blow off valve really loud. The most critical points are the Y-pipe where the TB is and the intercooler hoses. They could be loose. But since you double checked them I would think that one of the sensors has a poor signal or receives faulty information.

 

The MAFs are new. Been there done that. There is no misfiring, it is just down on top end with a lot of boost leak. I have ordered the Bosch boost sensor on the Y Pipe as it is only $40. Hopefully the ECU is just venting boost because of the high upper voltage from the sensor is throwing it out.

 

TT Crab. It looks like you were correct. Durametric reports the error wrong. It is P0238 according to Porsche. They also believe that the car is overboosting, which is triggering the diverter valves to vent the boost.

Now we have to work out why. Hopefully it is the boost sensor itself.

 

I expected durametric to be more reliable to be honest. So you just need to get a new sensor now. I've got no idea about the cost though. But I hope at least it solves the problem once and for all. Before you replace your boost sensor check your EGR valve... I have a feeling that it might well be it! Best of luck!