Cleaned map sensor still want clear
Hi there:
Basically this means that an oxygen sensor in bank 1 has detected a lean condition (too much oxygen in the exhaust). On V6/V8/V10 engines, Bank 1 is the side of the engine that has cylinder #1. The P0171 is one of the more common trouble codes.
This code is triggered by the first downstream (front) O2 sensor. The sensor provides a reading of the air:fuel ratio leaving the engine's cylinders, and the vehicles powertrain/engine control module (PCM/ECM) uses that reading and adjusts to keep the engine running at that optimum ratio of 14.7:1. If something is not right and the PCM cannot maintain the 14.7:1 ratio, but rather there is too much air, it triggers this code. 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 cracked vacuum or PCV line/connection
Faulty or stuck open PCV valve
Failed or faulty oxygen sensor (bank 1, sensor 1)
Sticking/plugged or failed fuel injector
Low fuel pressure (possible plugged/dirty fuel filter!)
Exhaust leak between engine and first oxygen sensor
Possible Solutions
A lot of times, cleaning the MAF sensor and finding/fixing vacuum leaks fix the problem. If you're on a tight budget, start there, but that may not be the fix for certain. So, possible solutions include:
Clean the MAF sensor. Consult your service manual for it's 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/repair as required
Inspect all hoses and connections in the air intake system
Inspect and/or test the intake manifold gaskets for leakage
Check for a dirty fuel filter and proper fuel pressure
Ideally you'll want to monitor short and long term fuel trims using an advanced scan tool
If you have access, you may want to run a smoke test
Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.
Thank you for using FixYa, have a nice day.
SOURCE: P0171 AND P0174 CODES KEEP
Same, here - P0171. It is found in the teamzx2.com website. It is under "common problems" and I am going to check the pvc valve and its pipe - which is most likely the culprit.
SOURCE: 99 RX300 Engine code keeps coming up lean
I just had the same thing happen to my 99 RX300. I replaced the MAF sensor and cleaned the throttle body. We cleared the codes and check engine light came on again... with a knock sensor code. Had to replace knock sensors. Found some great info on how to do that here. http://us.lexusownersclub.com/forums/index.php?showtopic=41266&mode=threaded Car drives great now!
SOURCE: P0171 code on 99 Ford Escort ZX2 2.0L
Check vacuum hoses to MAP sensor. They can get porous after a while. Also check hose to EGR valve.
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. .
SOURCE: ford explorer ,4 litre. have code of P0171
You could be right but before going to all that trouble of replacing the intake gasket take a close look at the MAF (Mass Air Flow) sensor. Also look for a vacuum leak downstream of the MAF sensor. The MAF sensor may be dirty especially if you are using an "oiled" air filter and it was over oiled. Remove the MAF sensor and clean it with electronic cleaner. Make sure it is dry before reinstalling. If it is damaged, replace it. Also replace the fuel filter as a partially clogged filter has been know to set this code on some vehicles. Check all vacuum hoses and replace as necessary.
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