What the P0171 code means. The P0171 OBD-II code means that, on the first bank of the engine, the fuel system is running weak or a vacuum leak exists near this side of the engine. A lean condition occurs when the engine either receives too little fuel or too much air.
How do I fix the code P0171 on my BMW?
- Replace the fuel pump or fuel filter.
- Change the fuel pressure regulator.
- Replace the powertrain control module.
- Change one or more injectors.
- Replace one or more oxygen sensors.
- Change the mass airflow sensor.
- Repair vacuum leak.
What does P0171 bank 1 system Too Lean Mean?
A P0171 code is set by your vehicle’s powertrain control module (PCM) when it detects that the air-to-fuel ratio of your vehicle is too lean. This means that the PCM is relaying that the engine is receiving too much air into the combustion chamber and not enough fuel.
What causes P0171 and P0174 codes BMW?
A vacuum leak is the most likely reason for a check engine light on and P0171 and P0174 codes stored.
What causes a BMW to run lean?
Your engine runs lean if your air-to-fuel mixture is too light – this means that the fuel in your ignition chamber is being igniting with too much air or too little fuel. Because your engine is running on less fuel than it should, it is running “lean.”
Is it OK to drive with P0171 code?
What Does Code P0171 Mean? Issue Severity: MODERATE– Extended driving with this code can cause internal engine damage. Repair Urgency: Get this code fixed as soon as possible to avoid damage to spark plugs, pistons, and catalytic converters.
Can bad spark plugs cause P0171?
If your sparks plugs have gone out, the OBD scanner should read the codes P0300 or P0171 which means lean running engine coupled with misfires.
Can a bad O2 sensor cause P0171?
When the ECM/PCM is having to add too much fuel based on input from the O2 sensor, the fault code P0171 will be sent to the ECM, which will trigger the check engine light to illuminate. This code could either mean that the oxygen sensor is detecting too much oxygen or too little fuel in the mixture.
Can a bad catalytic converter cause a P0171 code?
A bad catalytic converter wouldn’t in itself cause a misfire code, but if the cat. is partially blocked then exhaust gas flow will be impeded and that can cause an engine to misfire if all the old exhaust gas isn’t able to escape the cylinder before the new air/fuel charge is sucked in.
What would cause a P0171 code?
A P0171 code indicates the air-fuel ratio entering your engine block is not ideal. Two main issues typically cause this code. There is either too much air or not enough fuel in the lines to create the right ratio. When there’s too much air, you’ll often find a vacuum leak allowing an excess of oxygen into the line.
Is P0171 serious?
A lean fuel trim code like P0171 causes performance problems that can lead to costly damage, so it’s best to avoid driving with it. These problems can include bad fuel economy, poor engine performance, and even internal engine damage.
How much does it cost to fix a P0171 code?
You may get lucky with one of the simple repairs mentioned above. A broken vacuum hose sucking in air can be around $50, or a clogged fuel filter for $100. On the other hand, an oxygen sensor or mass air flow sensor can bring a bill of $400 to $500 dollars.
Can a dirty air filter cause a lean code?
How do you fix lean fuel?
Vacuum leak: Vacuum leaks can cause a lean fuel mixture. Inspecting and replacing damaged vacuum lines with good hoses and clamps can solve a lean problem. Clogged fuel filter: clogged fuel filters will limit the amount of fuel required by the engine.
Which o2 sensor is P0171?
P0171 is triggered by the engine bank 1 “upstream” oxygen sensor and P0174 is triggered by the engine bank 2 “upstream” oxygen sensor.
Can an exhaust leak cause a P0171 code?
If a car has a check engine light on and has P0171 and P0174 codes stored, the most likely cause is a vacuum leak. These codes are set by the car’s computer when it sees too much oxygen in the exhaust.
What side of the engine is bank 1?
Most commonly, bank 1 houses the front most cylinder on the engine cylinder 1, and bank 2 is the opposite side of the engine.
Can an exhaust leak cause a lean code?
When an exhaust leak is present, the ECU can detect a false lean signal and respond incorrectly, adding fuel in an attempt to remedy the problem, but further exacerbate it.
Can a bad fuel pump cause a lean code?
If the fuel pump can no longer keep the pressure and flow at the fuel rail at or above the fuel regulator relief pressure it can cause a lean code.
Can a bad throttle body cause a lean code?
Typical vacuum leak culprits that cause this so called lean condition can be your intake manifold leaking, cylinder head gasket leaking, valve cover gasket or gaskets leaking, throttle body gaskets leak, carburetor spacer leak, and of course you can’t forget any of the many, many engine’s vacuum fittings, hoses and or …
What happens if engine runs too lean?
A rich-running engine is caused by excess fuel and lack of air, whereas an engine running lean is the exact opposite – the engine lacks enough fuel or there is an excess of air. These conditions can cause trouble down the line, potentially causing knocking or leading to complete engine failure if not resolved.
Is bank 1 sensor 1 up or down?
Bank 1 Sensor 1 means Upstream Right/Rear;Bank 2 Sensor 1 means Upstream Left/Front;Bank 1 Sensor 2 means Downstream Right/Rear;Bank 2 Sensor 2 means Downstream Left/Front.
How can I tell which O2 sensor is bad?
A decrease in fuel efficiency can be a telltale sign that an O2 sensor is not performing as it should. This can happen because of a fuel mixture that is either too lean or too rich. Such a swing in A/F ratio is a sign that an upstream or control sensor is faulty.
Can a bad PCV valve cause P0171?
Ford Expedition lean codes could caused by a leaky PCV hose. If a car has a check engine light on and has P0171 and P0174 codes stored, the most likely cause is a vacuum leak. These codes are set by the car’s computer when it sees too much oxygen in the exhaust.
How do I fix code P0171 and P0174?
- Disconnect the air cleaner assembly from the throttle body.
- Spray some carburetor cleaner on a clean shop rag.
- Use the rag to clean around the throttle body and valve.