Volvo S40 The S40 is Volvo's most affordable sedan with all the amenities of a luxury sports car.

Rough Idle/Stumbling Acceleration

Old 07-10-2019, 05:43 PM
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Join Date: May 2019
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Question Rough Idle/Stumbling Acceleration

Girlfriend's 2003 S40 1.9T with 82K, I'm getting a misfire at idle and a slight stumble on acceleration. I now have these codes : P0403 and P0442. The gas cap was replaced recently. I had a P0172 but that was fixed with a new MAS and an exhaust purge valve. I changed the spark plugs (NGK iridiums)and cleaned the throttle body when I serviced it last. I'm not getting any misfire codes. Does anybody have an idea of what I'm missing? I'm new to Volvos. Thank you in advance!
Old 07-10-2019, 08:59 PM
Join Date: Mar 2012
Location: Ridgefield, CT
Posts: 4,793

the P0403 points to the "EGR control circuit" and the P0442 points to a leak in the evap system. Sounds like either or both has created a vacuum leak. The P0442 can be caused by the vacuum line going all the way bay to the evap cannister (by the passenger rear tier) - that's probably what I'd look at first. You may need to do a smoke test to find it - google "J Tube Volvo" for some ideas.
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