I've got this fault cominig up:

17958 - change pressure : control deviation P1550 - 35 - 10 - - - intermitant

on my 1999 Octavia 1.9 SLX TDI.

Thanks in advance.

Got this from ross tech wiki:

17958/P1550/005456 - Boost Pressure Controle Valve (N75): Control Deviation

Possible Symptoms

• Irregular behaviour
  
• Reduced power output
  
• Limp mode
  

Possible Causes

• Hoses/Pipes incorrect connected, disconnected, blocked or leaking
  
• Charger Pressure Control defective
  
  • Solenoid Valve for Boost Pressure Control (N75) defective
    

  [*]Turbocharger defective

Possible Solutions

• Check Hoses/Pipes to/between Components
  
• Check Charge Pressure Control
  
  • Check Solenoid Valve for Boost Pressure Control (N75)
    

  [*]Check turbocharger

Retrieved from "http://wiki.ross-tech.com/index.php/17958/P1550/005456"

HTH Ian

Does it go into limp mode? If so could be the sticky turbo problem.

could be a split vacuum/pressure hose somewhere between the n75 and the turbo,

I would check pipes first as that costs nothing.

Then I would change the N75 and lastly the turbo as that is the most expensive.

In truth I reckon it's the sticky vane problem common to the TDI's. Skoda will tell you it's a new turbo required but there are companies that will strip, clean and service it for much less than the cost of a new turbo.

Does it go into limp at about 3000rpm?

Youv'e posted a code but gave no symtoms, it would be helpful if you could.

Ian

Thanks guys.

I'll check thepipes and N75 but I suspect the vanes sticking.

Isn't there a chemical that you can fill the turbo with to clean it out?

I suspect mine to have rust in it though as the car has stood for a while. I hear malt vinegar will remove rust so couldn't I fill it with that for a day or two?

Yes it does go into limp mode.

Limp mode and that code makes me think sticky turbo. Hown intermittant is it? Does it tend to happen when the revs are about 3,000 as Lex Dysia mentioned?

There is a place in Ross on Wye who sorted my car but they sent the turbo to someone else to rebuild rather than doing it themselves. there is a description of how to sort it knocking about, I think it was posted by Greg123 and is on TDIclub or something. I may have been drinking and can't remember exactly, or type very well for that matter

Some times at happens around 3000 rpm but more often at just over 4000 rpm.Some times it will rev to 5000rpm no problem.Seems to happen more when it's hot.

Turbo is sticking then.

As for a turbo rebuild, someone else has just had a quote for about £200 from Turbo Technics.

As for a turbo rebuild, someone else has just had a quote for about £200 from Turbo Technics.

I suppose thats not too bad if they remove it as well but I'd rather have a go myself. I've never had a play with a turbo before so should be quite interesting.