What causes engine code P0171?
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.
How much does it cost to fix P0171?
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. A bad fuel pump can be really expensive costing around $600 to $800.
Will misfire cause lean?
This means the engine runs erratically on that one cylinder or not at all. The engine tries to compensate for this cylinder not firing and can cause the engine to run rich, or lean. Common causes of a misfire are spark plugs, wires, coil, fuel pump, fuel injector, vacuum leak, cap and rotor.
Can an exhaust leak cause a P0171 code?
An exhaust leak upstream of the O2 is kind of unlikely to cause a p0171, as it would have to be siphoning ‘clean’ air in via venturi effect. A head gasket leak or cracked head will allow the coolant to be burned.
Can bad spark plugs cause lean?
One of the main symptoms of bad spark plugs is unburnt fuel which is not really caused by a rich condition rather incomplete combustion but seeing that the fuel is being dumped in the exhaust the o2 sensor may believe it to be so and counteract the problem by subtracting fuel from the mix, hence creating a lean …
Can spark plugs make car run lean?
A common symptom of your car running lean is that your spark plugs are clean or turn white. Spark plugs are generally a brown or grey color, which is caused by normal ignition.
Can a bad coil cause lean?
In order to compensate for the absence of this cylinder, the engine runs lean or rich. A misfire can be caused by spark plugs, wires, coils, fuel pumps, fuel injectors, vacuum leaks, caps, and rotors.