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exhaust gas recirculation malfunction help


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  • 3 weeks later...
  • 5 months later...

I have a 97 legacy outback 2.5. Got the same code. Replaced EVERYTHING, and properly cleaned every hard and rubber line. Solenoid, EGR, and BPT replaced and vacuum tested. Still getting horrible gas mileage and the P0400 code pops up again and again. Even tested the O2 sensors on the multi meter, and they are operating perfectly. What the hell is next? Cat back exhaust? Or black electrical tape overy the check engine light?

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There are two sides of the EGR system, the mechanical side and the ECU monitoring side.

 

If I can cycle the EGR by hand while the car is idling and it acts like it's going to stall, then the valve is working. I will always start by replacing the tiny in line filter that is in the vacuum line going from the intake to the passenger side strut tower. At the same time, I will replace the BPT mounted above the EGR valve. If the code returns, it's likely the vacuum solenoid the ECU triggers to open the EGR valve, is bad.

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  • 1 month later...

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.. 

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Have you checked the port in the exhaust manifold.  It could have carboned over.  Remove the egr valve and poke a wire down both ports to make sure it is clear all the way from the inside of the exhaust manifold to the inside of the intake manifold.

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Oh yes, did that. Used my "guitar string" pipe cleaners and picks and cleared all carbon build up in all of the lines and ports. The lines that are removeable were removed and thoroughly cleaned, and the ones that can not be removed were cleaned out. I might take it all apart again and see if any loose chunks have gotten wedged in somewhere, but hard to believe on a 50,000 mile motor that this should be such an issue. 

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