Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - herald
I have a 54 plate Vw passat 1.9 Tdi with the AWX engine, it has started loosing power when accelerating hard on the motor way, it seems to hit a level and then it won't go faster and the revs won't pick up. When I come off the motor way it's stays like this until I switch off and then is fine again, today I have been out and when I accelerated hard again the engine management light came on and the display says 'emission workshop'. After switching off the management light stays on but runs ok. It has full vw history and otherwise runs fine. Heeeeelp
Thanks

Andrew

Top Reply

Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - cws

17964/P1556 - Charge Pressure Control: Negative Deviation

Possible Symptoms
  • Reduced power output
  • Limp mode

Possible Causes
  • Boost Pressure too Low
  • Hoses/Pipes incorrect connected, disconnected 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

All Replies

Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - Peter D

You need a diagnostic read to identify the problem. It is no good guessing, find a Vag independant specialist and see what is flagging up. Regards Peter

Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - herald
Think I will need to do that, just been out in it and the temp gauge is flicking from normal temp to zero not sure if this is related but it's never happened before, will get it booked in, what price am I looking at to read codes?
Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - Railroad.

The symptoms do sound like the turbo vanes or vane ring is sticking caused by excess soot and corrosion build up in the exhaust turbine. If this does prove to be the case don't be easily drawn in to buying a new turbo. Often the problem can be cured by giving the turbo a good clean, but this does mean dismantling it.....

Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - herald
Thought about the turbo being faulty, but I can pull over switch off the car and the fault(not the fault light) clears, I was thinking the car is going into limp mode. And then resetting
Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - Railroad.

Thought about the turbo being faulty, but I can pull over switch off the car and the fault(not the fault light) clears, I was thinking the car is going into limp mode. And then resetting

Which is exactly what it will do if the turbo vanes were sticky. The turbo is a centrifugal air pump, or blower. Its purpose is to blow air into the air intake thereby creating a boost and increase in air intake pressure. This results in increased engine power output. However, there is of course a drawback. This boost pressure must be controlled, because if it isn't then too much boost will cause serious damage or even destruction of the engine. On a VW this boost is controlled by varying the angle of the vanes in the turbo exhaust turbine. The steeper the angle the more effect they have, and when the angle of the vanes is flatter they'll provide no boost at all. If the vane ring is sticking then the ECU cannot control the boost. The ECU will then take action by reducing the engine power to prevent damage, so the power loss you are experiencing is itself not a fault.

If I were you I'd search the forums to see if anyone near you has VCDS. I do and I'm in Hampshire if that helps. With VCDS you can monitor the actual turbo boost against what the ECU expects it to be and display it on a graph making it easy to read and understand. If the actual boost pressure vastly exceeds the expected pressure which should peak at about 2100mbar then a problem with the turbo vane ring or a vacuum leak should be suspected.....

Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - herald
Hi thanks for the detailed reply, unfortunately I am in Lancashire there is a good independent near to me I will get it booked in tomorrow and let you know. Out of interest do you think the temp gauge issue could be related? It only started when the management light came on,
Cheers
Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - Railroad.

Temperature sensors are a common failure on these, and the modified sensors are green in colour. It will be more than a good idea to change it in any case, but I can't say I've ever heard of a faulty temperature sensor causing the problem you have.....

Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - herald
Ok thanks, probably just one of them things

thanks again
Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - herald

Had codes read today and the only one showing was P1556 (boost pressure variation) the management light has now gone out and the temp gauge is back too normal. Going to have a good look at the vacuum pipes and turbo pipes

herald

Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - herald
Had a good look today can not see any vacuum pipes leaking, going to have a look at the turbo I think, anyone got an ideas of fault code P1556
Ta
Andrew
Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - cws

17964/P1556 - Charge Pressure Control: Negative Deviation

Possible Symptoms
  • Reduced power output
  • Limp mode

Possible Causes
  • Boost Pressure too Low
  • Hoses/Pipes incorrect connected, disconnected 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
Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - cws

I would start with checking all of the turbo vac lines (the small, rubber pipes). Check they're all connected and check for any obvious splits. To be on the safe side, you may want to replace them (you can by 3mm and 5mm internal diameter silcione hose from ebay which is a better alternative and vastly cheaper than what dealers sell).

Also check the vacuum line for the brakes - a split here can also lead to a loss of vac pressure.

The site below is an excellent guide to fault finding:

sites.google.com/site/1810martin/home/b5-vnt-turbo...s

Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - herald
Hi thanks for the great replies I am going to have a look tomorrow after work and see if any pipes a split or loose , I will let you know what I find.
Andrew.
Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - archiepea

Hi

I live in your area and wondered if you could let me have the nale of the good independent garage you mentioned (I know it was a couple of years ago) as I have a few jobs that need attention on my B5.5.

Thanks very much indeed

Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - archiepea

Hiya

I have a loss of power problem, much as described in the (rather old) thread) and occasional eml on and 'emissions workshop' message.

Its an 05 B5.5 1.9tdi (130bhp) with an AWX engine code

You mentioned a good independent VAG specialist in Lancashire (for diagnosis and possible jobs)?

Are they still in existence... and would you (or anyone else out there) be able to let me have details on any good garage in Cheshire, Manchester, Lancashire or even Staffordshire.

Help please, if you can (see below)

[We've recently spent over 1000 pounds on the car (clutch with dial mass, timing belt and water pump + the radiator needed changing) as the car had been running very well, and we had hoped to keep it for another year or two.. :( ]

Thanks very much

Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - HuskyDG

Hi There, I saw your post in reply to the above VW earlier in the year and wondered if you had any idea with mine. Very similar symptoms, emmission workshop light on with an intermittent gradual loss of power and blue black smoke. Loss of power can be reset with the ignition key. Light stays on. Fault code suggests Air Mass Meter, but this has been replaced and only temporarily cleared the fault. Could a faultly wire to Air Mass meter cause similar symptoms? Dont want to take it to VW unless I have to. I see that you are in Hampshire, so am I ,

Any help would be appreciated.

Many thanks

Dave

Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - dieselnut

To Dave, I would check the EGR valve on the inlet manifold & make sure it is closing ok.

Suggest you remove it & give a good clean.

Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - HuskyDG

Thanks for your help, but that has also been done along with a new EGR sensor! Did'nt make any difference. I think I need to have the wiring checked out. Anyone know of a good Auto Electrician in Hampshire?

Thanks Dave

Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - Railroad.

HuskyDG - I'll try to help you if I can. I have VCDS which is the complete diagnostic software for VAG. You can email me at railroad153@hotmail.com. I'm a few miles north of Southampton.

Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - Warby1

Hi Andrew,

Did you get to the bottom of your emissions issue? I have a very similar problem, emissions light combined with a intermittant temp guage issue, although I am not experiencing any loss in power. I'm about to take my car in but would like to know what cured yours. Many thanks in advance.

Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - 659FBE

Change the temperature sender which is under the EGR valve. It's a dead easy job, if a little awkward to get to, and cheap. GSF sell good pattern parts (the revised design is green - the useless originals are black) and buy a new "O" ring seal at the same time. Use the specified G12+ coolant mixture to top up.

659.

Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - Warby1

Hi 659,

Thanks for your info. I'm a muppet when it comes to cars (had to google what an EGR valve is) so I googled how to do it. Looks very awkward so I'm going to have to get the garage to do it. Do you think the failure of this sensor could cause the emissions workshop message? Thanks.

Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - 659FBE

A failure of this sensor will indeed flag a dashboard warning. When the sensor is changed, the message will disappear after a couple of start/stop cycles. There is then no real need to erase the error code from the ECU although it will remain for posterity unless it is cleared.

The VAG/Bosch software is clever - the sensor is a dual unit (4 pins), one half providing dashboard temperature indication and the other half providing data for the engine controller. When a failure is detected, the warning message is flagged and the ECU uses a scaled version of return fuel temperature to derive the missing coolant temperature as a reversionary mode. This is why engine running is largely unaffected by this fault.

If your original sensor has a black body it will be faulty. The delicate and brittle NTC thermistor beads were stupidly potted in hard epoxy and the thermal cycling caused them all to fracture and fail open circuit. The green senders have a soft encapsulent.

659.

Edited by 659FBE on 03/01/2013 at 23:04

Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - Warby1

Thanks for the info, appreciate it. Local garage confirmed the sensor was being reported US and they replaced it for £45 all in.

Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - Craig Birrell

i know this was a long time ago but didyou ever get the problem sorted?

can you remember what it was i am having the exact same issue with 54 plate 1.9tdi passat.

any information be much appreciated!!

Vw passat 130 Tdi - Vw passat 'emissions workshop' light on - Big John

Does yours shudder when turning the engine off? [EDIT - sorry just seen this is March - however for others, if engine shudders on turn off then there is a vacuum leak/issue affecting EGR, turbo variable vanes and anti shudder valve]

Edited by Big John on 24/11/2018 at 23:32

 

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