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Q: P0171 code

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I have rebuilt the top end completely and have added short pipe headers still have cat and i keep getting the 02 bank 1sensor 1 to lean p0171 and I've replaced iac map tps and checked lined and intake for leaks and nothing runs fine idles fine doesn't get hot but still runs this code please help

My car has 199682 miles.
My car has an automatic transmission.

Hi there:

In general, the P0171 OBD-II error code indicates that on the first bank of the engine, the fuel system is running weak or a vacuum leak exists near this side of the engine. This could be caused by multiple problems ranging from a vacuum leak, mass air flow sensor, a bad fuel injector or other components that have bad electrical connections. It’s also possible that the change to the "short pipe" has altered the performance of the engine. Typically any change in exhaust system hardware is accompanied by a tuning upgrade to the ignition or fuel / air mixture to compensate. If you haven’t completed that step, you might want to contact the aftermarket manufacturer of the "short pipe headers" to see what they recommend for your 1999 Ram 1500.

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