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Anonymous Posted on Apr 23, 2009

Diagnostic Codes p0171 bank 1, and p0174 bank 2 (too lean)

Ford expedition, 99, 5.4, has been idling rough and stalling. I received a p0171 bank 1 and p0174 bank 2. I can hear an air leak but not sure where. Aside from that, I recently changed the heater core, but now smell slight coolant. could the 2 be related or is it just the fuel filter?

  • 3 more comments 
  • Anonymous Apr 23, 2009

    how do i replace the oxygen sensors? and should i replace the pcv valve also?

  • Anonymous Apr 23, 2009

    Could the Mass Airflow sensor be the culprit?

  • Anonymous Apr 23, 2009

    Thanks for all of your help!

  • Anonymous Apr 25, 2009

    Just an update: After taking a closer look and following the air leak sound, we found a big hole in the Elbow of the PCV valve.... when we covered the hole, the idle was normal again! Hooray for that! Unfortunately no one sells just the elbow... had to put out $65 for the complete assembly... oh well. Thanks again for your help.

  • Anonymous Mar 31, 2014

    where is bank one

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1 Answer

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  • Master 1,201 Answers
  • Posted on Apr 23, 2009
Anonymous
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Those codes are for the oxygen sensors, lean fuel mixture on both banks. Change them, problem with stalling and rough idle should go away.

  • Anonymous Apr 23, 2009

    The sensors are just screwed into the exhaust pipes.Unplug the the wire connector, use an oxygen sensor socket, or wrench, if not in a tight spot, and unscrew them.

    Also disconnect neg. battery terminal, before you unplug them.

    If there is an anti theft feature built into the radio, better get the code for it, cause once the battery is disconnected, you will loose preset stations, and it won't come back on.

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Keeps throwing up trouble codes p1506,p1151,p0302,p0171

Definition of Diagnostic Trouble Code P1506 Audi: Closed Throttle Position Switch Does Not Open/Short to Ground BMW: Idle-Speed Control Valve Opening Solenoid Control Circuit Signal High Ford: Idle Air Control Overspeed Error (see P0507) Jaguar: Idle Air Control System RPM Lower Than Expected - B Bank Kia: IAC Valve Opening Coil Voltage High Lincoln: Idle Air Control Overspeed Error (see P0507) Mazda: Idle Air Control Overspeed Error Mercury: Idle Air Control Overspeed Error (see P0507) Porsche: Throttle Jacking Unit Lower Mechanical Stop, Signal Implausible Volkswagen: Closed Throttle Position Switch Does Not Open/Short to Ground Volvo: IAC Valve Opening Signal
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Definition of Diagnostic Trouble Code P1151 Audi: Bank1, Long Term Fuel Trim, Range 1 Leanness Lower Limit Exceeded BMW: Oxygen Sensor Heater Circuit Signal Intermittent (Bank 2 Sensor 1) Ford: Lack Of Heated Oxygen Sensor Bank 2 Sensor 1 Switches - Sensor Indicates Lean Jaguar: Lack of H02S-21 switch, sensor indicates lean Land Rover: Lambda control limit bank 2.Implausible signal/condition Lincoln: Lack Of Heated Oxygen Sensor Bank 2 Sensor 1 Switches - Sensor Indicates Lean Mazda: Lack Of Heated Oxygen Sensor Bank 2 Sensor 1 Switches - Sensor Indicates Lean Mercury: Lack Of Heated Oxygen Sensor Bank 2 Sensor 1 Switches - Sensor Indicates Lean Subaru: HO2S-12 Heater Circuit High Input Toyota: Coolant Path Clog Up for Coolant Heat Storage System Volkswagen: Bank1, Long Term Fuel Trim, Range 1 Leanness Lower Limit Exceeded
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Definition of Diagnostic Trouble Code P0302 Category: Powertrain Definition: Cylinder 2 Misfire DetectedNote: This definition of P0302 is applied to all manufacturers
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Definition of Diagnostic Trouble Code P0171 Category: Powertrain Definition: System Too Lean Bank 1Note: This definition of P0171 is applied to all manufacturers
0helpful
1answer

What can i check next with codes p0012 n p0171

P0012 "A" Camshaft Position - Timing Over-Retarded (Bank 1)



P0171 System too Lean (Bank 1)
0helpful
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Rough idle, stalls, extremley rich

Maybe sensor is not for a bigger engine
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2answers

I have a 98 expedition 5.4 l . after warm up runs ruff at idle. codes p0171,p0174.

P0171 - Fuel system lean bank 1
P0172- Fuel System lean bank 2

First steps- search for a vacuum leak and verify proper fuel pressure.
8helpful
1answer

Rough idle vibrates and po171 code service engine soon. [email protected]

Hi, a Ford P0171 is a LEAN code for cylinder bank 1, and P0174 is a LEAN code for cylinder bank 2. These codes commonly occur on many Ford vehicles, and are set when the powertrain control module (PCM) sees the air/fuel mixture is running too lean (too much air, not enough fuel).
When the Check Engine Light comes on, either one of these codes, or both, may be found when a code reader or scan tool is plugged into the vehicle diagnostic connector. IF the vehicle is driven long enough, typically both codes will be set.
A P0171 lean code for bank 1 is the cylinder bank on the RIGHT (passenger) side of the engine on Ford vehicles with a V6 or V8 engine and rear-wheel drive.


A lean fuel condition may exist if the engine is sucking in too much air and/or the fuel system is not delivering enough fuel. If bad enough, a lean fuel condition may cause lean misfire, a rough idle, hesitation or stumble when accelerating, and/or poor engine performance.
Unmetered air can enter the engine through a vacuum leak, a dirty airflow sensor that is not reading airflow accurately, an EGR valve is not closing and is leaking exhaust into the intake manifold, an EGR valve that is allowing too much flow (because the EGR differential pressure sensor that monitors EGR flow is faulty and is under-reporting EGR flow).
If the problem is not enough fuel, the underling cause may be a weak fuel pump, restricted fuel filter, leaky fuel pressure regulator or dirty fuel injectors.

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98 ford expidition 4.6 codes current po171 po174 and has po304 and po308 veh idles little rough repaire vaccumat rear of throttle body,is this a lower plenium leak veh has 177,00 mileson it

hi guess your engine has lack of power also a rough tick over ?your codes tell me you are running lean on bank 1and2 this can be due to many things its a matter of checking of one at a time 1 a bad coolant temp sensor 2vacuum leak 3 dirty injectors also reach over the top of your engine behind the intake dead centre of the windscreen there is a 9odeg rubber elbox check for a hole if thats your problem its only 3usd good luck please rate this answer thanks pete
5helpful
2answers

Check engine light on

Generally when these codes appear it is due to insufficient fuel pressure. Test your fuel pump to ensure it is within specs. Have you changed your fuel filter?
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