2001 Audi A4 P1555 code

LenoVan

New member
Joined
Apr 26, 2022
Location
Canada
TDI
A4
I have bought this car last year. Yesterday when I derived it nearly 10KM, step on the accelerator but kept nearly 2000.
I stop and restart, the accelerator is working, but when I derived 2km, the situation happened again.
After the next day, when I start the car, some smoke comes near the Three-way catalyst.

This is the error Code.
What should I do the check the car and repair it?

17963/P1555 - Boost pressure Control: Upper Limit Exceeded
Possible Symptoms

  • Reduced power output
  • Limp mode
Possible Causes
  • Boost Pressure too High
  • Hoses/Pipes incorrect connected, disconnected, blocked or leaking
  • Charger Pressure Control defective
    • VNT (variable nozzle turbo): nozzles stuck
  • Solenoid Valve for Boost Pressure Control (N75) defective
Possible Solutions
  • Check Hoses/Pipes to/between Components
  • Check Solenoid Valve for Boost Pressure Control (N75)
  • Check / Clean / Replace Charge Pressure Control
    • Check / Clean mechanism for variable nozzles
 

Scubanero

Veteran Member
Joined
May 30, 2007
Location
Calgary AB
TDI
2005 Passat Wagon
What you are seeing is turbo limp mode. Since it appears to be high pressure, not low, you need to look at the controls and the inlet vanes. There are lots of threads dealing with similar problems. Search and you will find.
 

LenoVan

New member
Joined
Apr 26, 2022
Location
Canada
TDI
A4
What you are seeing is turbo limp mode. Since it appears to be high pressure, not low, you need to look at the controls and the inlet vanes. There are lots of threads dealing with similar problems. Search and you will find.
Thanks for your response.
Two months ago, When I derived the car the engine light was on, and the engine passenger side has caught fire. I guess the reason is the high temperate in the three-way catalyst and some oil upon it.
After this accident, I replaced MAF, the oxygen sensor.
Today the same thing happened again. I have searched in many forums, the most answer is the Hoses leak, but when this leak happens,
Boost Pressure too High can't be high. I am very confused.
 

Scubanero

Veteran Member
Joined
May 30, 2007
Location
Calgary AB
TDI
2005 Passat Wagon
Failure of the inlet guide vane control will also trigger a limp mode. In that case, look into the N75 relay and associated vacuum tubing.
The other possibility is that the vanes are corroded and stuck in place.
 

LenoVan

New member
Joined
Apr 26, 2022
Location
Canada
TDI
A4
Failure of the inlet guide vane control will also trigger a limp mode. In that case, look into the N75 relay and associated vacuum tubing.
The other possibility is that the vanes are corroded and stuck in place.
Thanks. I have checked the N75 and associated vacuum tubing.it's ok.
So air leak is not the reason for "P1555 - Boost pressure Control: Upper Limit Exceeded" ?
The pressure cannot be discharged, so the pressure is too high, rather than the leakage of the pipeline, which needs to be supplemented?
 

zzdiesel

Veteran Member
Joined
Dec 10, 2010
Location
sask. mostly now Wa.
TDI
05 passat tdi Geared BSM and Bewcam 2nd 2005 deleted ,converted and bew cam stage 2 Malone3 tune.
There have been known to be problems when the vac tubing was routed incorectly, particularly at the N75.
 

Scubanero

Veteran Member
Joined
May 30, 2007
Location
Calgary AB
TDI
2005 Passat Wagon
Possible Causes
  • Boost Pressure too High
  • Hoses/Pipes incorrect connected, disconnected, blocked or leaking
  • Charger Pressure Control defective
    • VNT (variable nozzle turbo): nozzles stuck
  • Solenoid Valve for Boost Pressure Control (N75) defective
Possible Solutions
  • Check Hoses/Pipes to/between Components
  • Check Solenoid Valve for Boost Pressure Control (N75)
  • Check / Clean / Replace Charge Pressure Control
    • Check / Clean mechanism for variable nozzles
 

MEgearhead

Veteran Member
Joined
Aug 6, 2016
Location
Virginia
TDI
B5.5, 4L, 4G
The first step should be to connect a hand vacuum pump to the turbo actuator and see that it moves smoothly through it's range of motion with increasing vacuum.

If it doesn't, the mechanism needs to be cleaned.

If it does, remove the hand pump and reconnect the vacuum hose then run the turbo actuator test using VCDS and see if it moves from stop to stop. If the actuator works with a hand pump but not automatically during the test the issue is in the vacuum control. Verify the vent line is not plugged. If not then try a known good N75 valve.
 
Top