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Enes, Volvo Master Technician
Category: Volvo
Satisfied Customers: 5559
Experience:  18 yrs+. experience as Volvo & ASE Certified Master Technician.
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my s40 2.0 diesel has rough idle. injector replacment?

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my s40 2.0 diesel has rough idle. i tried to clean up throttle body and mas sensor, but still same. i then disconnected each fuel injector seperatly and 3 of them resulted in a further drop in revs, however the 4th when disconnected, did not alter the idle, is this a sign that the 4th injector is needing replaced? forgot to say that when car idling, it wont rev above 1100 revs,( i think car is in "limp home mode") will this correct itself if new injector is fitted? Car is a 2005 volvo s40 2.0d. (Also there is no warning lights / engine diagnostic lights come on on the dash.)

Enes :

Hello and welcome to our web page here my name isXXXXX a Certified Volvo Car Expert Mechanic.I'm going to try today to answer your question.

Enes :

yes fuel injector can be bad or clogged up

Enes :

but you must first read error codes with scanner to make sure there is no electrical sensor going bad

Enes :

I would not replace injectors now until you test first and hook up scanner you will be going to Volvo garage to run those test


have just noticed couple of air bubbles in fuel line just before fuel filter. could this be cause, and just need fuel system primed to remove bubbles?

Enes : No I don't think is air
Enes : Most important is to get for right the test of check engine light
Enes : When you get that engine diagnostic code that create all problems and make also injector not fire correct
Enes : before you spend money on injectors to guess you must run that diagnostic scanner test at volvo garage it will help a lot to what part is causing it

can a normal garage do the diagnostic test? want to try avoid main dealer prices. what could have caused air in fuel? had no prob previously.

Enes : Any garage can do it who has good diagnostic scanner
Enes : well it can air from cracked fuel line somewhere sucking air
Enes : But you will not know until you see thr fault codes

Ok. cheers XXXXX XXXXX help. thanks again.

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