Basically this means that an oxygen sensor in bank 1 detected a lean condition (too much oxygen in the exhaust).
You will more than likely not notice any drivability problems, although there may be symptoms such as a lack of power, detonation (spark knock), and/or a hesitation/surge on acceleration.
A code P0171 may mean that one or more of the following has happened:
•The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
•There could be a vacuum leak downstream of the MAF sensor.
Possible solutions…
•In the vast majority of cases, simply cleaning the MAF sensor does the trick. Consult your service manual for its location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
•Inspect all vacuum and PCV hoses, replace if necessary
•Check for a dirty fuel filter and proper fuel pressure
SOURCE: vehicle failed emissions testing
You need to replace the intake upper plenum gaskets. There is two pieces, a top cover with one big silicone o-ring gasket and a lower half with six smaller silicone o-rings for the individual intake ports. You can buy these as a set, just for this job. Start this job by removing the wiper blades, then release all the screws, (including the ones that support the wiper motor), that hold that big black plastic valence at the back of the engine compartment. Pull that out of the way, you will have to pull the windshield washer hose through it, just disconnect it on the engine side, now you have access to the plenum. It's a pretty easy job now to remove and replace both halves, just a bunch of 8mm screws hold it all together. Take notes or digital pics along the way so you can pop it all back together. My only caution would be; when you have it apart, do not drop anything in the intake port! I always stuff kleenex in these while I'm working in case something slips out of my hands. Also, don't over tighten, it's all plastic. If you don't want to do it yourself, a shop should charge about an hour and a half, plus the codes must be reset and the van driven until all the monitors are ready.
SOURCE: what does engine fault code po171 system too lean bank 1 mean thanks
i think its the oxygen sensor (pre cat) in exhaust
SOURCE: PO171 error code System too lean bank 1
Here are some possible causes, I would start with anything related to replacing the intake.
Air leaks in intake manifold, exhaust pipes or exhaust manifold
Fuel control sensor is out of calibration
Low fuel pressure (fuel filter clogged, pressure regulator failure)
One or more injectors restricted or pressure regulator has failed
O2 sensors contaminated, deteriorated or has failed
Vacuum hose is disconnected, broken, leaking or loose
SOURCE: got code p0171 system too lean (bank 1)
This is probably referring to problems with your bank 1 oxygen sensor. Without the vehicle make, model and year I can't tell you where it is located. However, if you replace your front oxygen sensor that should clear up the problem. Also, if you do replace it, I always run some fuel injector cleaner through a full tank of gas at the same time. Hope this helps!
SOURCE: have p0130 and p0133 codes 98 toyota tacoma
I would check the O2 sensor, and if it checks bad, replace it, and clear the trouble codes. If the light comes back on, you may need to check further. .
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