Question about Toyota 4Runner

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Runs lean, code 25, already changed VAF and O2 sensor

How can I tell if an injector is clogged on a 95 4runner 3.0L

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Only if the car is missifire on the cly and you have spark and compresure. replace the injetor

Posted on Apr 17, 2009


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2003 pickup. What are the probable causes of DTC P0171?

Since you have replaced the sensor, my first guess would be low fuel pressure or a vac leak.
Code 171 means the computer can not make the fuel mixture rich enough to make the sensor switch from lean to rich and back.

Jun 24, 2015 | Dodge Cars & Trucks

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Ford dtc codes

white porcelain on plugs means lean mixture. run the fault codes and check for MAP/MAF/VAF sensors --HO2s and O2 sensor problems .

Sep 08, 2014 | 1994 Ford Econoline

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PO174 AND PO171\

code p 0171 refers to system too lean bank1===causes ---intake /exhaust leaks--AIR system---MAF/VAF sensors --fuel pressure/pump--injector/S=== HO2S
code p 0174 refers to system too lean bank 2====causes intake /exhaust leak---fuel pressure/pump---injector/s---AIR system---hose connection/s
the fuel pressure is adequate
The HO2S is the heated oxygen sensor in the exhaust manifold /pipe before the cat converter
( is responsible for the fuel ratio settings )
you may have to pull the injectors to have them cleaned and tested
the maf/vaf sensor may have to be replaced as well

Apr 11, 2017 | 2004 Cadillac SRX

1 Answer

How do I fix a code P0171 (too lean)?

code p0171 refers to system too lean bank1===causes intake/exhaust leak-AIR system--MAF/VAF sensors---fuel pressure/pump/regulator---injectors---HO2S. To understand the fuel mixture there is a direct ratio between the air and the fuel and it is 14:1 air to fuel . Anything either side is too rich or too lean. manifold leaks/vacuum hose leaks--Mas air flow sensor, Volume air flow sensor all tell the CPU what the ratio is so any unit not performing will throw out the ratio. If the fuel pressure is too low or high the injectors do not squirt properly at the rpm required

Nov 30, 2013 | 2000 Pontiac Grand Prix

1 Answer

I am getting PO171 and PO174 codes on my 2006 mustang gt with the 4.6L v8.

the codes refer to system too lean on banks one and two===causes --intake /exhaust leak--MAF/VAF sensors fuel pressures/pump---injectors HO2S ( heated oxygen sensors in the exhaust manifolds before the cat converters
the fuel trim is what the computer sets at after a long term run and not after a few trips around the block
it is the HO2S sensors that control the mixture by reading the exhaust gas composition and reporting to the ECM which adjusts the injector operation
they could be getting a bad reading is the flex section of the exhaust manifold pipe is cracked in side of the braid covering

Jul 21, 2017 | 2006 Ford Mustang GT

2 Answers


P0171 System too Lean (Bank 1),Here's what is listed for the code.OXYGEN SENSOR.

Sep 10, 2012 | 1997 Toyota Camry

1 Answer

Service engine light comes on. Code says lean bank one and two. Changed map sensor, and front o2 sensors. Did not fix problem. I have heard the same from other people and they have not gotten it fixed...

besides the heated oxygen sensors being faulty, lean mixture codes also refer to intake/exhaust leaks ( cracked flex section of exhaust pipe at manifold , low fuel pressures /pump, faulty injectors , MAF/VAF,wiring and ECM

Jul 27, 2017 | 1999 Chevrolet Silverado 1500

1 Answer

Have this code PO171, what does this mean.

Not sure that the O2 sensor was bad. It sounds like it was telling you that side of the exhaust system was picking up a lean mixure at the O2 sensor. The O2 sensor was doing its job by telling you the mixture changed. If the O2 sensor was bad, it would say low voltage range for that sensor, or open curcuit.
Now the car has had time to do its diagnostic sweep, it is telling you the same thing, but from a different sensor...the fuel mix is too lean. Air/spark/and fuel is what you need in the correct amounts. In your car, the ECM engine control module controls this by taking readings from all the sensors several hundred times a second.
Mechanically, you have a few options. Change the fuel filter...under the car on the passenger side. It is an easy job.
Change the fuel pressure regulator. This keeps the fuel at 4 BAR so the fuel injectors can do their job correctly. This job just needs a screw driver to pop off the clip that holds it in place. No hoses need to be removed. It is on top of the intake manifold, in-line with a metal fuel line and a rubber one.
The fuel injectors could be clogged up on one side of the engine. Run some fuel injector cleaner through a tank of gas. Also, listen for a constant ticking sound at each injector. If one sounds off PAR, then replace it.
The fuel pump may not be giving you enough power. However, the readings seem to be localized to one side, so I doubt it.
Start with the easiest thing, and see if it works. Also, you will need to get yourself a VAG scan tool. It is the only one with codes in it for all of your VW systems, not just engine codes like the ODB scanners. You can get a nice one for $50 on-line.
Good Luck!

Feb 24, 2010 | 2002 Volkswagen Passat

3 Answers

2001 Toyota corolla hesitates on acceleration

Basically this means that an oxygen sensor in bank 1 detected a lean condition (too much oxygen in the exhaust).

Mar 27, 2009 | 2001 Toyota Corolla

1 Answer

Running rich and lean

the codes ur getting will be thrown by a vacume leak make sure u dont have a vacume line leaking or split also check ur pcv valve for clogging

Jun 18, 2008 | 1995 GMC Safari

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