Code 0171 on banks 1 and 2 for a 1995 Crown Vic with 220,000 miles. Code means system too lean. Should I: Replace fuel filter and see if code goes away? Take to my mechanic to check fuel pressure? Live with it? Not sure if fuel filter has ever been replaced. Thanks --
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Re: How do I cope with "system too lean"
If you have never replaced the fuel filter with 220,000 miles I definitely think it is time to. You could try a good fuel system cleaner STP or similar, this may not help but it will not hurt. You may opt to check your fuel lines for debris and change if needed.
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code p 0171 refers to system too lean bank 1==causes ---intake /exhaust leak---AIR system if fitted--MAF/VAF sensors--fuel pump/pressure---injector/s ---HO2S ( heated oxygen sensor in the bank one exhaust manifold before the cat converter)
code p 0181 refers to fuel temperature sensor A --range /performance problem===causes ---fuel temp sensor
code p 0171 refers to system too lean bank 1===causes ---intake / exhaust leak---AIR system---MAF/VAF sensor ---fuel pressure / pump/ regulator--injectors---heated oxygen sensor (HO2S)
code p 172 refers to system too rich bank 1====causes ---intake blocked ---EVAP canister purge valve ---fuel pressure --- EGR system--- injectors---HO2S
as the HO2S is in both codes , check/ replace it as it reports to the ECM for air /fuel mixture settings and if faulty it can set to too lean or too rich or swap between the extremes
code p 0171 refers to system too lean bank 1===causes --intake/exhaust leak---AIR system---MAF/VAF sensor---fuel pressure/ pump/ pressure regulator---injector/s---heated oxygen sensor (HO2S unit in the exhaust manifold or before the cat converter
If the engine is running well then consider replacing the HO2S unit as that reports to the ECM that then adjusts the mixture for that bank by altering injector amounts and timing
all the rest affect both banks but the code is bank 1 specific
P0171 and 174 System Too Lean
Basically this means that an oxygen sensor in banks 1 and 2 detected a lean condition (too much oxygen in the exhaust).
These codes may mean that one or more of the following has happened:
•The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
•There could be a vacuum leak downstream of the MAF sensor.
•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.
•Inspect all vacuum and PCV hoses, replace if necessary
•Check for a dirty fuel filter and proper fuel pressure
P0358 Ignition Coil H Primary/Secondary Circuit Malfunction
Code P0358 is for cylinder #8.
Inspect the spark plug, coil, and coil boot on that cylinder for signs of damage. Replace as needed.
If no problems are found with the components, check the wiring harness from the coil to the Powertrain Control Module (PCM).
Potential Causes: Failed coil or boot
Failed spark plug