P0171 OBD-II Trouble CodeTechnical Description System Too Lean (Bank 1) This diagnostic trouble code (DTC) is a generic powertrain code. It is considered generic because it applies to all makes and models of vehicles (1996-newer), although specific repair steps may be slightly different depending on the model. So this engine code article applies to Toyota, Chevrolet, Ford, Nissan, Honda, GMC, Dodge, etc. 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.

You'll want to also read our article on short and long term fuel trims to help understand the operation of the engine. Note: This DTC is very similar to P0174, and in fact your vehicle may show both codes at the same time. You will more than likely not notice any drivability problems, although there may be symptoms such as: a lack of power A code P0171 may mean that one or more of the following 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 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. 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 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 Related P0171 DTC Discussions2001 Nissan Maxima 20th Ann Ed Auto P0171 P0135 and P0100CODES TODAY:

P0171 System too lean (Bank 1) 02 Heater circuit (Bank 1, Sensor 1 P0100 Mass Air Flow Circuit I previously replaced Idle Air Control Valve & it ran fine for 2 months now as you see above, my problems are back. 2002 Toyota Rav4 with 2 banks and a lean code P0171Ok, I have a 02 Rav4 2.oL with 2 banks and P0171 on bank 1. spike air cleaner honda shadowI've had this problem running lean for few years now and possibly due to this lean condition I had to replace a Cat 3 times already. air duct cleaning milford ct5 years ago, then 2 years ago and then year ago under warranty. air duct cleaning lebanon tnThe shop that replaced it under the warrant... 2004 Toyota Rav4 P0171I have a 2004 Rav4. I get repeated P0171 codes.

Engine will idle rough after a battery disconnect. It has a lack of power on acceleration. 2 winters ago, I had to change the fuel pump. This started around that time. I have cleaned the MAF sensor. When I run my scanner, I noticed that the o2 s... My caravan is stalling trouble code p0171Indicating trouble code po171dodge... What are my options.... P0171 Chevy c2 2007Necesito.ayuda me.aparese.un. P0171 Chevy 2007 cambie sensores.de.oxigeno .v�lvula iac y sigue el. Need more help with a p0171 code? If you still need help regarding the P0171 trouble code, please postHome > Fuel Economy is Down With the price of gasoline, you don’t want to ignore this kind of problem for long. When fuel economy is down, you may find any number of codes: P0172 and/or P0175 are rich codes, and indicate a general rich air/fuel condition. The underlying cause may be anything that increases fuel delivery, such as excessive fuel pressure, a defective fuel pressure regulator, plugged return line, or leaky injectors.

Decreased airflow from a dirty air filter or restricted air intake misleads the mass airflow sensor or engine management system into believing the engine is using more air or is under more load than actual. Misfire codes P030X, where X indicates the cylinder number that is misfiring. Misfire codes are bad because they mean a whole cylinder full of air/fuel mixture is wasted every time a cylinder fails to fire. The cause may be a worn or dirty spark plug, a bad plug wire, a weak ignition coil in a distributorless ignition system (DIS) or coil-on-plug (COP) ignition system, or a dirty or dead fuel injector. Misfires can make an engine run rough and reduce horsepower every time it happens. Worse yet, the unburned fuel that passes right through the engine goes into the exhaust. When that fuel reaches the catalytic converter, it will ignite and may cause the converter to overheat and suffer damage. Misfires are one of the two leading causes of catalytic converter failures (the other is leaky exhaust valves).

Oxygen sensor codes (P0130 to P0167), or oxygen sensor heater code (P0036 to P0064) indicate a fault with that sensor. If the O2 sensor fails, it usually causes the engine to run rich leading to poor economy, pollution, and catalytic converter failure. Never replace an O2 sensor without testing it first. Figure 3 shows failed Bank 1 Oxygen Sensors. P0115 to P0119 point to a problem with the coolant sensor. The coolant sensor tells the engine computer the temperature of the coolant. The engine computer needs this information to adjust the fuel mixture and ignition timing as the engine warms up. If the coolant sensor is faulty and tells the computer the engine is cold when it really is hot, the fuel mixture will be too rich. Fuel economy will drop like a rock and the engine will pollute. P0100 to P0104 are Mass Airflow (MAF) sensor codes. The mass airflow sensor measures airflow into the engine. If it is not reading correctly, the air/fuel mixture won’t be right. This is an expensive sensor to replace, so in many instances cleaning the delicate sensor wire with an aerosol electronics cleaner can return it to normal operation.