Hey Everyone,

I have a 2008 Honda Fit with 208,000 miles and I’m dealing with an intermittent P0171 (System Too Lean). To better describe the issue, here is the exact scenario:

In the morning, when the engine is cold, the car starts perfectly. Idle is smooth, acceleration is strong, and it drives normally. Even with stop-and-go traffic at red lights, everything feels fine. However, after driving for about 30 minutes, if I turn the engine off and try to restart it 5–10 minutes later, the engine cranks but does not start. If I wait another 5–10 minutes, it will eventually start, but it struggles badly. Acceleration is very weak, the engine feels like it is choking or starving, and it sometimes feels like it might stall.

The P0171 code appears intermittently — I can clear it and it may stay off for quite a while before coming back.

I also removed and cleaned the MAP sensor with spray and reset the ECU using an OBD scanner. After that, the problem seemed fixed for one day — acceleration improved and the check engine light stayed off — but the next day the same symptoms returned and the P0171 check engine light came back.

I’m trying to determine whether this is caused by a vacuum leak (PCV hose, intake manifold gasket, brake booster hose, etc.), a fuel delivery issue, or a sensor problem.

Any advice or similar experiences would be greatly appreciated.