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Matt
Matt, Engineer
Category: VW
Satisfied Customers: 21079
Experience:  Mechanical Engineer with 20 years experience in the auto industry, 8 yrs in formula 1 engine testing
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Vw golf: 1.9tdi..engine management light..an emissions workshop

Customer Question

hi hav a mk5 vw golf 1.9tdi 2004 the engine management light cum on other day an emissions workshop appeared on dash its went off an cum back on again a few times seems 2 b stayn on this time light yellow. have u any ideas wat this is havnt had chance 2get dias as work 2 many hours in the day. thanks
Submitted: 6 years ago.
Category: VW
Expert:  Matt replied 6 years ago.
Hello

On any car if you get a check engine light or other fault light this typically means one or more of the sensors has failed or has a faulty connection.

The ECU senses this and may put the car into 'limp home' mode which typically limits the revs and the amount of power available. Usually the car is safe to drive for a short distance as the mode is intended is intended to get you home without incurring any engine damage

The quickest route to repair is to have the car plugged into a diagnostic machine which will read off the fault code stored in the ECU (providing the light is still on at this point) and indicate which sensor has failed or whether the fault is more serious.

You can do a very rough and ready check yourself by unplugging sensors one at a time and seeing if any of them change the driving condition which would indicate the most recently unplugged sensor is the faulty one. This method is not foolproof though and reading a fault code off is the better method.

Customer: replied 6 years ago.
rite light went out again there on way 2 work gona c if it cums on 2mrow an get it checked an il get back 2 u. thanks
Expert:  Matt replied 6 years ago.
Hello

if the light is intermittant then its possibly a poor connection

Try checking all the connections to the engine sensors one at a time, remove each one and examine for signs of corrosion or damage and a squirt of contact cleaner ( not WD40) will also help.
Matt and 5 other VW Specialists are ready to help you
Customer: replied 6 years ago.
rite got plugd in 2day when light was on but its not shown any fault codes up when he reset it light went out he took it drive an never came back on but on my way 2 work 2nite it cum back on again!!!! puzzled lol thanks
Expert:  Matt replied 6 years ago.
Hello

Are there any driveabilty issues when the light is on such as poor acceleration or bad idle quality ?
Customer: replied 6 years ago.

no car doesnt lose any power an runs just fine u wont fink there was anything wrong just dis light an emissions workshop message

Customer: replied 6 years ago.

just so u no ur gona actually get payed lol there is a wee leak of oil just wer the egr valve is wud this be anything thanks

Expert:  Matt replied 6 years ago.
Hello

The EGR valve shouldn't be leaking any oil so its worth pulling it off the engine and giving it a flush out with some brake cleaner and checking its seals/ replacing the gasket
Customer: replied 6 years ago.
there like a dome of a thing on top of it were a wee breather pipe goes below the dome theres two wee small holes in the front an back of it that seems 2 b were the oil is cumin out? thanks
Expert:  Matt replied 6 years ago.
Hello

the dome houses a diaphram thats driven by engine vacuum , this diaphram has a couple of breather hole on one side so if its leaking oil its possible that the diaphram has had it which will mean the EGR won't be working very well - as this is an emissions device you may not notice much difference when its repaired / replaced.

Customer: replied 6 years ago.
rite well took egr vavle off an cleand it out wit brake cleaner cleaned all the oil away from the diaphram an stuck egr vavle back on got tin of egr vavle cleaner an sprayd it in2 it holdn revs at 2000rpm when id half the tin through it i turn it off an started it up again an the light never came on happy days but on my way 2 work its back on again. had gd look round seals an noticed no damage only place i can c were the oil is cumin from is them 2 holes near top of diaghram. wat do u fink? thanks
Expert:  Matt replied 6 years ago.
Hello

do a double check of the EGR valve electrical connections for corrosion and the wiring for any insulation damage but it might time to invest in a new EGR valve

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