Ethan Posted April 10, 2017 Share Posted April 10, 2017 So I have replaced my whole EGR system. Replaced EVERY line, EGR, Solenoids, EVERYTHING. All seems to be functioning fine, running good, but still bad gas mileage. The Check engine light goes off for about 4 or 5 days then turns back on with the same EGR code. Is the next step new exhaust system? The exhaust has 238,000 miles on it, but the motor only has 50,000 on it. I'm stumped. Could it be a bad computer since I used the original one when I replaced the motor, or do you all think maybe the exhaust is just old and full of crud? Any info and or advise would be awesome. Thanks.. Quote Link to comment Share on other sites More sharing options...
wtdash Posted April 11, 2017 Share Posted April 11, 2017 (edited) Hi, Why are you focusing on EGR? online: P0300 SUBARU - Random Cylinder Misfire Detected Possible causes: Faulty spark plug (s) Faulty ignition coil (s) Clogged or faulty fuel injector (s) Intake air leak Fuel injectors harness is open or shorted Fuel Injectors circuit poor electrical connection Ignition coils harness is open or shorted Ignition coils circuit poor electrical connection Insufficient cylinders compression Incorrect fuel pressure Read more: https://www.autocodes.com/p0300_subaru.html P.s don't cross-post, post on another thread, etc. Stick to one so the Forum can focus on it. Edited April 11, 2017 by wtdash Quote Link to comment Share on other sites More sharing options...
06SubLegTx Posted April 11, 2017 Share Posted April 11, 2017 So I have replaced my whole EGR system. Replaced EVERY line, EGR, Solenoids, EVERYTHING. All seems to be functioning fine, running good, but still bad gas mileage. The Check engine light goes off for about 4 or 5 days then turns back on with the same EGR code. Is the next step new exhaust system? The exhaust has 238,000 miles on it, but the motor only has 50,000 on it. I'm stumped. Could it be a bad computer since I used the original one when I replaced the motor, or do you all think maybe the exhaust is just old and full of crud? Any info and or advise would be awesome. Thanks.. Read my post: 2006 -2009 Legacy 2.5i Limited Rough Cold Idle Quote Link to comment Share on other sites More sharing options...
keith3267 Posted April 11, 2017 Share Posted April 11, 2017 P0300 is for a random misfire, so plugs, coils and injectors are less likely at fault. More likely is something shared by all cylinders like the crankshaft position sensor, camshaft position sensor or fuel pump/filter/regulator. Quote Link to comment Share on other sites More sharing options...
06SubLegTx Posted April 11, 2017 Share Posted April 11, 2017 Hi, Why are you focusing on EGR? online: P0300 SUBARU - Random Cylinder Misfire Detected Possible causes: Faulty spark plug (s) Faulty ignition coil (s) Clogged or faulty fuel injector (s) Intake air leak Fuel injectors harness is open or shorted Fuel Injectors circuit poor electrical connection Ignition coils harness is open or shorted Ignition coils circuit poor electrical connection Insufficient cylinders compression Incorrect fuel pressure Read more: https://www.autocodes.com/p0300_subaru.html P.s don't cross-post, post on another thread, etc. Stick to one so the Forum can focus on it. Sorry Quote Link to comment Share on other sites More sharing options...
wtdash Posted April 11, 2017 Share Posted April 11, 2017 (edited) Sorry Why? If yours directly addresses the issue, then No Problem. My P.S. is/was directed @ the OP - Ethan - he has 3 posts w/the same info: 2 New threads and one 'hi-jack' of another. Edited April 11, 2017 by wtdash Quote Link to comment Share on other sites More sharing options...
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