Check Engine light came on and the codes said P0171 P0174
System running to lean bank one and bank to
does this mean i have to replace the oxygen sensors?
I changed the coils and spark plugs because it said it was
misfiring.
You likely have a vacuum leak. These two codes are the most common codes your car will throw. The likelihood of your 02 Sensors being bad is almost equal to your odds of winning a 10-spot Keno. Your next step is to perform a smoke test to check for leaks.
FWIW - the only 02 Sensors that should ever be used on a BMW are Bosch.
Last edited by All2kool; 03-27-2018 at 07:40 PM.
It definitely should not automatically mean that.
Lean codes on both banks generally indicates an intake leak.
IF you are mechanically inclined, and a DIYer,
first remove rubber intake boots, then squeeze them and all associated hoses,to expose hard to locate cracks,
which cause unmetered air intrusion-leading to lean fuel mixtures.Thus causing misfires and lean fuel mixture codes.
Replace items where cracks are found.
IF not,
then I suggest a smoke test performed at a reputable BMW shop with a pro smoke machine.
Last edited by MIKYZZ4; 03-27-2018 at 07:50 PM.
Use bosch o2 sensors. As mentioned above p0171/174 are most likely caused by a vacuum leak or other unmetered air leak like a broken intake boot. It is recommended to replace o2 sensors after 100k. You can just replace the upstream sensors because those are the two that control fuel mixture. This will not likely resolve the issue. You need to do/get a smoke test.
Sent from my SAMSUNG-SM-G870A using Tapatalk
Yeah, the DISA o-ring is, in fact, no an o-ring in this traditional sense. It’s actually molded into the DISA. Yes, it takes some time to fully remove the “o-ring.” I’d replace it (if the DISA is good) with an o-ring from German Auto Solutions.
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