2015 Subaru Legacy 2.5 runs great except on cold start. Cold start below 32f it stalls, after couple more tries stars and runs fine. Cleaned the throttle body, cleaned the mass air flow sensor and cleaned the egr valve. No change. The scan tool shows P1603 and P1604. but other then these codes engine runs after warm up.
Stalls on cold start 32F or below
- Thread starter davbri59
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- Feb 9, 2025
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I Have 1993 Legacy and I don't have the codes, because I don't have a reader however its doing about the same thing. Normally very dependable and runs great though it's not starting and pushing up to 2500 RPMs and gradually lowering to idle. I think it's a vacuum leak with the manifold, or spark plug seal gromets need to be replaced. I am going to tighten the exhaust manifold nuts 1/2 turn and see if this makes any difference. If the exhaust bumps a snow drift sometimes it creates air leak, and this affects the O2 signaling.