The dreaded P1174 and P1171

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James Hicks

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Dayton Ohio
2004 SE7 Disco 2
147xxx
Full rebuild

I have had intermittent 1174 and 1171 codes pop up. They usually pop up after I hit the highway. Never city driving.
I have replaced the MAF. Air filter. Air box.
I have done an intake smoke test. No leaks.
I did a sea foam treatment the other day and noticed a good leak from the header to the Y pipe.
I have a new gasket on the way along with new front O2 sensors.
My theory is that when the car is under a load, it sucks air into Y pipe causing the O2 to read high O levels making it seem lean, causing the P1174. Does this seem like a legitimate theory?
 

joey

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Sounds correct to me. Any air leaks prior to the cats will cause issues. Your probably do not need the 02 sensors, just the gasket.
 

helkebir

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I just recently had the same problem with my Discovery with the identical codes a month ago. I needed them to be cleared so I can get my vehicle to pass the smog test. I went thru 2 new MAF sensors that turned out to be bad. I returned to my original MAF sensor and took it apart and cleaned it thoroughly with Electrical cleaner (not MAF cleaner) and has been running code free for the last 2000 miles.
 

MatttheHatt

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I was getting those two codes, even after changing several sensors out. Turns out my alternator wasn't putting out the voltage I needed.at the battery, it was only low to mid 12v. Swapped the alternator with the one from my other Disco and high low 14v. Codes gone...

Sent from my SM-G965U1 using Tapatalk
 

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