Code P0171

You could have them check the upper O2 sensor.

[quote:74ed6342a7="annehbrown53"]Working with a 1999 Honda Accord 4 door Automatic 4 cylinder.

History

1 - Check engine light went on at 121478 miles
Response - 120,000 mile maintenance.

2 - Recall check at 122829 miles
Response - inspect ignition switch key - okay

3 - Check engine light on again at 131443 miles
Response - replace fuel pressure regulator (s/b#03-079)

4 - Check enging light on again at 131443
Replace all 4 fuel injectors.

5 - Check engine lignt on again at 131539 with Code P0171
Response - clear cherk engine light

6 - Check engine light on again at 132000

What should we check now?

Thanks so much[/quote:74ed6342a7]

A code P0171 indicates the engine is running lean. This means there is too much air and/or not enough fuel. You can confirm the engine is running lean by looking at Short Term Fuel Trim (STFT) and Long Term Fuel Trim (LTFT). Normally, STFT and LTFT should be plus or minus 5 to 10 from zero. If STFT and/or LTFT are more than about +12, it indicates the engine is running lean. Negative numbers (-12 or more) indicates the engine is running rich.

A lean fuel condition can be caused by:

* O2 sensors-low voltage

* Low fuel pressure due to a weak pump or leaky fuel pressure regulator. (use a fuel pressure gauge to check fuel pressure at idle)

* Dirty fuel injectors. (try cleaning the injectors)

* Vacuum leaks at the intake manifold, vacuum hose connections or throttle body. (Use a vacuum gauge to check for low intake vacuum)

* Leaky EGR valve. (Check operation of EGR valve)

* Leaky PCV Valve or hose. (Check valve and hose connections)

* Dirty or defective Mass Airflow Sensor (MAF). (Try cleaning the MAF sensor wires or filament with aerosol electronics cleaner. Do NOT use anything else to clean the sensor, and do not touch the sensor wires)

Good Luck

[quote:c2993176b2="rasmataz"][quote:c2993176b2="annehbrown53"]Working with a 1999 Honda Accord 4 door Automatic 4 cylinder.

History

1 - Check engine light went on at 121478 miles
Response - 120,000 mile maintenance.

2 - Recall check at 122829 miles
Response - inspect ignition switch key - okay

3 - Check engine light on again at 131443 miles
Response - replace fuel pressure regulator (s/b#03-079)

4 - Check enging light on again at 131443
Replace all 4 fuel injectors.

5 - Check engine lignt on again at 131539 with Code P0171
Response - clear cherk engine light

6 - Check engine light on again at 132000

What should we check now?

Thanks so much[/quote:c2993176b2]

A code P0171 indicates the engine is running lean. This means there is too much air and/or not enough fuel. You can confirm the engine is running lean by looking at Short Term Fuel Trim (STFT) and Long Term Fuel Trim (LTFT). Normally, STFT and LTFT should be plus or minus 5 to 10 from zero. If STFT and/or LTFT are more than about +12, it indicates the engine is running lean. Negative numbers (-12 or more) indicates the engine is running rich.

A lean fuel condition can be caused by:

* O2 sensors-low voltage

* Low fuel pressure due to a weak pump or leaky fuel pressure regulator. (use a fuel pressure gauge to check fuel pressure at idle)

* Dirty fuel injectors. (try cleaning the injectors)

* Vacuum leaks at the intake manifold, vacuum hose connections or throttle body. (Use a vacuum gauge to check for low intake vacuum)

* Leaky EGR valve. (Check operation of EGR valve)

* Leaky PCV Valve or hose. (Check valve and hose connections)

* Dirty or defective Mass Airflow Sensor (MAF). (Try cleaning the MAF sensor wires or filament with aerosol electronics cleaner. Do NOT use anything else to clean the sensor, and do not touch the sensor wires)

BTW what was the code on No.6 CEL

Good Luck[/quote:c2993176b2]

wow hard to believe the dealer missed the most common cause of this code on this vehicle, especially since honda has a tsb on it. most common problem for this is the fuel pressure regulator and the vacuum hose going to it.

there is an updated fuel pressure regulator kit