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Matt
Matt, Engineer
Category: Volvo
Satisfied Customers: 21270
Experience:  Mechanical Engineer with 20 years experience in the auto industry, 8 yrs in formula 1 engine testing
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I have a 2006 s40 and just had the 90k service done. A few

Customer Question

I have a 2006 s40 and just had the 90k service done. A few days later a whistle sound from front passenger side started and today a check engine light came on. Was told it could be an oil trap clog and to remove the dip stick and reinsert it. What does this do and should I be driving this with the check engine light on?
JA: Does the light stay on, or does it blink?
Customer: Stays on
JA: Are you fixing your S40 yourself? What have you tried so far?
Customer: No, I always take it to the dealer
JA: Anything else you want the mechanic to know before I connect you?
Customer: I don't think so, I was just surprised when the light came on and concerned if I should drive it until I can get in to the dealer..
Submitted: 6 months ago.
Category: Volvo
Expert:  Matt replied 6 months ago.

Hello

to get a whistling then this could be an airleak after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for and can lean the engine out causing rough running.

As its a mechanical fault it tends not to turn on the fault light and you can sometimes hear a 'hissing' or whistling noise with the engine running.

Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.

The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane or brake cleaner around each joint in turn. If the engine rev's up you've found your leak.

Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.

Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.