I've got a check engine light on and the code it's giving me is a P0171 which means my "System is Lean." Anyone have any ideas on what exactly this could be and how would I fix it? My guesses would be a faulty O2 sensor or clogged fuel injectors/pump/filter... Thanks

 

um hello.. this board sucks ******* for newbs

 

if your "system is lean" then of course for some reason the ecu is saying that you're not getting enough fuel.

all those things you've stated could be a problem. but if you checkd the code you should've had the book to look up the procedure for troubleshooting it. if worse comes to worse, i can look it up at work, but you wont get the results until tomorrow evening.

try clearing the code to see if it comes back. maybe u'll be lucky and it was just a one time thing.

 

hey thanks for the response. i actually went to jiffy lube to get the code so i dont have the book. i have already reset the ecu and it came back on after driving about 100 miles so i'm guessing it's not going away. i'll try some injector cleanser tomorrow. it'd be helpful if you could give me some details tomorrow. thanks again

Hunter

 

Here it is. DTC P0171: System too lean. Possible causes:
- Fuel Pump insufficient flow/pressure
- Fuel Feed Line clogged, leaking
- Fule Pressure Regulator stuck open
- Fuel Filter clogged
- Fuel Injector clogged, air inclusion
- Gasoline doesn't meet Owner's Manual spec.
- Primary HO2S (Sensor 1) deteriorated
- MAP Sensor range/performance* - 96 Model
- EGR System malfunction (too much flow)* - D16Y5 engine
- Valve Clearance
- Exhaust leak

Troubleshooting Guide:

1. Check fuel pressure
- If ok, then go to step 2
- If fuel pressure is too high then check fuel pressure regulator and fuel return pipe.
- If fuel pressure is too low then check the fuel pump, fuel feed pipe, fuel filter, and fuel pressure regulator.

2. Check the Primary HO2S (except D16Y5 engine M/T)
- Start engine and hold at 3,000 rpm in N or P until the radiator fan comes on.
- Check the Primary HO2S (Sensor 1) output with scan tool.
- If voltage is less than 0.3V or more than 0.6V then Replace HO2S (step 3 if not)

3. Check for sticking or leaking EVAP purge control solenoid valve:
- with a vacuum pump, apply vacuum to the EVAP purge control solenoid valve from the intake manifold side.
- If it does not hold a vacuum then replace the EVAP purge control solenoid valve.
- If it does, go to step 4.

4. Check MAP sensor output (96 model)
- Turn the ignition switch ON
- Check the MAP with a scan tool.
- If it does not indicate atmospheric pressure then replace the MAP sensor.
- If it does go to step 5.

5. Check the response of the MAP sensor:
- Start the engine and check the MAP with the scan tool.
- If a MAP of 40.0 kPa (300 mmHg, 12.0 InHg) or less indicated within one second after starting the engine then go to step 6.
- If not then replace the MAP sensor.

6. Check valve clearances

7. Check the EGR system (D16Y5 engine)

8. If they are OK, replace the fuel injectors.

Note: This is straight from the book at my shop. Hope it helps.