2003 Ford Taurus stalls at idle

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.

SOURCE: 1999 ford taurus emission reading p0171 and p0174

just tune up ur car periodicly, clean filter. clean ur sparkplug.

SOURCE: 2005 Ford Taurus SE 3.0L V6 OBD Codes P0171 and P0174

The P0420 code is a Catalytic converter efficiency code check the compression.Swap the #1 injector to a different location to see if the code follows.Test the coilpak. A cracked exhaust manifold is the most likely cause p0171 and 0174 Induction air leaks, vacuum or some kind fuel restriction, weak fuel pump, restricted fuel filter etc.You also could have an exhaust leak near the upstream o2 sensor. If youtake it in they will probably use smoke to find out where the leak is.

Ronny Bennett Sr.

• 6988 Answers
• Posted on Jan 05, 2010

SOURCE: what do these trouble codes mean p0171 and p0174

po171 is system too lean,bank 1,po174,is system too lean,bank 2,It sounds like a fuel pressure problem.

SOURCE: OBD Codes P0401; P0171; P0174. EGER valve sensor

p0401 egr flow insufficient. p0171 system to lean ( bank 1 ). p0174 system to lean ( bank 2 ). common problems that trigger p0401--

• Restriction in the EGR passages, usually caused by carbon buildup
• The EGR Valve is defective
• Lack of proper vacuum or electrical signal to the EGR valve
• Malfunctioning EGR Vacuum supply solenoid
• Lack of proper EGR system feedback to the computer from the:
  
  • Manifold Absolute Pressure Sensor (MAP)
  • Differential EGR Pressure Feedback Sensor (DPFE)
  • EGR Valve Position Sensor (EVP)
  • EGR Temperature Sensor - p0174--
  • In the vast majority of cases, simply cleaning the MAF sensor does the trick. 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 also
  • Inspect all vacuum and PCV hoses, replace if necessary
  • Check for a dirty fuel filter and proper fuel pressure p0171- and p0174 are about the same.