Service Engine Soon: Code P0171

1slow370

if you're still having the problem this is what the FSM says
Intake air leaks
• A/F sensor 1
• Fuel injector
• Exhaust gas leaks
• Incorrect fuel pressure
• Lack of fuel
• Mass air flow sensor
• Incorrect PCV hose connection

also P0171 is the passenger side bank only not both banks, driver's side is p0174 the ecu takes two trips to throw the light and 3 trips with identical driving conditions to shut off the light by itself if the problem stops.

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JeanaVilee

I've also had this code (on a different car) from a bad O2 sensor, but given that it is reporting it on both banks that doesn't seem to be the problem here.

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jtgarza3

i was wondering if you have got this problem fixed, i to am having that same problem i get on the gas aggressive it studders around 4-5k rpms and sounds like im red lining then. i noticed this after i was low on gas and filled up so i was thinking it is bad gas.

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DrEvil

I had that code pop up about two months after installing my hfc's. I thought that it was due to the O2 sensors and the new hfc's but it turned out that the cause was due to a slipped hose clamp on the short ram that attached to the throttlebody. The ram slid out of the coupler and the engine was sucking in unmetered air. I replaced the flimsy coupler with a nice silicone hump coupler from Z1 Motorsports and hanen't seen that code since.

Daishi

this only happens after the car sits for a long time? if so could be a leaky injector

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Jordo!

Either bad vac leak somewhere near or in front of primary O2 (could also be exhaust leak just past it that causes a lean read), faulty MAF sensor, or bad O2.

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401-370z

I'm getting that code as well but my car won't start... died as I was driving it and that's the only code... would that code cause it to not start?

Corsairprime

My problem was caused by fake Denso Iridium FXE24HR11 spark plugs. The electrodes on all of these fake plugs melted to a gap of .075 to .080. I did buy new plugs from NGK, the Laser Iridium DF8H-11B plugs and this fixed my issue. I also replaced the front O2 sensors in the midst of troubleshooting my troubles. I had rough and misfiring issues with the fake plugs. I checked and tightened the entire intake tract and secured all vacuum hosing with fresh clamps to eliminate and vacuum leaks. The fake plugs were confirmed by the fact that the writing could easily be scraped off. The real Denso plugs do not let the lettering scrape off, the letters are under the glaze on the insulator. The fake plug issue is widespread on the web.

Hope this can help you ID some of your issues. Best of luck.

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