Question about Ford F-450
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Posted on Jan 02, 2017
P0171 is system too lean bank 1, P0174 is too lean bank 2, and 302 is misfire bank 1. Look for vacuum leaks. If you don't find them, put a vacuum gage on it can check. The P0171 is almost always a vacuum leak. If not other possibilities are front O2 sensor is too old and should be replaced (if mileage is greater than 100k then replace). Try injector cleaner. Misfires are usually bad spark plugs, but could possibly be caused by insufficient fuel. I've never had a car of mine in bad enough shape to have that error.
Posted on Oct 24, 2008
Bank one is toward the front of the vehicle. Sounds like the heated oxygen sensors have gone bad. The Oxygen Sensors are located in the exhaust pipe and require a special socket to remove and replace.
Posted on Jan 16, 2009
O171 MAF (Mass Airflow Sensor) Just try cleaning this part it usually solves that problem without having to buy new part.
0174 Both are mass air flow sensors. The other problem can be a vacuum leak Check PCV valave and all vacuum lines. Also make sure fuel filter and fuel pump are working correctly. You can clean the MAF with some brake cleaner make sure it is dry before you install it back
Posted on May 28, 2009
SOURCE: p0171 and p0174 codes
P0171 System too Lean (Bank 1)
P0174 System too Lean (Bank 2)
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. Excessive oxygen readings in the exhaust will set lean codes. This does not mean that the oxygen sensors are defective. It is a common mistake for people to replace oxygen sensors when lean codes are present. Just because the code is related to oxygen sensor readings, it doesn’t mean that the oxygen sensors are bad. If both of these codes are stored this means that both banks of the engine have excessive oxygen in the exhaust. If the oxygen sensors are replaced it’s most likely that the same codes will reappear. It is very uncommon for two oxygen sensors to fail at the same time.
Therefore the most likely cause of P0171 and P0174 codes is a vacuum leak. The source of a vacuum leak can be one of many things. The most common cause of a vacuum leak is a leaky hose. Vacuum hoses over time can become dry and brittle. The rubber deteriorates and can leak causing a vacuum loss. Many times a leaky vacuum hose can be found by listening for a hissing sound. A large vacuum leak can even make the car run rough at idle. In some cases it will not idle without feathering the gas pedal.
Posted on Sep 10, 2009
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