Question about 2003 Toyota Corolla
Engine check light on and emission report says DTC4 FAIL. Also, emission report says P0171 System too lean (Bank 1)
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Posted on Jan 02, 2017
SOURCE: engine light is on
You probably have a vacuum/air intake leak.
With the engine idling, spray very short bursts of starting fluid/ether around the intake and surrounding engine bay and wait a second. If the engine surges, there is an intake leak which you can identify by closing in with the ether.
ALWAYS USE VERY SMALL SQUIRTS IN A DIRECTED AREA AND WAIT FOR IT TO VENTILATE BEFORE TRYING AGAIN ELSEWHERE
Put car outside,
do this in a ventilated area,
have a blanket handy in case of a backfire fire.
DONT spray ether idirectly into the air intake when the engine is running
A bad intake leak is audible by a hissing sound. A bad rubber hose is often the cause.
Any vacuum hose under the hood can cause this.
The PCV valve which can also cause this code when faulty, should be replaced as a matter of course. its in the valve cover and only costs a coupla bucks. They are easy to fit.
Hope that helps
pls be conservative with the ether its not good for your engine in large doses!!
Posted on Jan 07, 2009
Hi. You need to clean the Mass Air Flow Sensor.
This is an easy job.
Get a can of throttle body or brake cleaner spray at your local auto parts store.
Open the hood, and locate the air filter box. follow the tube from the filter box towards the engine. Look for a small black box with 2 screws holding it to the air tube, Remove the wire connector and observe inside the sensor with a flashlight. You will see 2 small wires, and they will appear fuzzy or dirty. Spray the interior with the cleaner until the wires are nice and clean. Do not use compressed air, you will damage the sensor. Put it all back together and drive it.
This will def fix your issue. This is a vey common problem. If you do it yourself, you will save 70 + bucks.
Thanks for choosing FixYa, and a FIxYa rating for my assistance would be greatly appreciated.
Posted on Jan 23, 2009
Trouble Code: P0171
Fuel System Too Lean (Bank 1)
A/FS or HO2S is contaminated, deteriorated or it has failed Air leaks after the MAF sensor, or in the EGR or PCV system Base engine "mechanical" fault affecting one or more cylinders Exhaust leaks located in front of the A/FS or HO2S location Fuel system supplying too little fuel during cruise or idle (faulty fuel pump or fuel filter) Fuel injector (one or more) dirty or pressure regulator has failed Vehicle driven low on fuel or until it ran out of fuel
Posted on Jul 23, 2009
SOURCE: bank 1 too lean
ALL CARS fixes are guessing and hoping at best. 1st thing is it a 4 cylinder or a v6. if its a v6 and you have bank 1 lean but NOT bank 2 lean, then you are probably looking for a vacuum leak affecting only bank 1. Stuck injector will NOT ause this code without also setting a misfire code. Cars use fuel trim. Basically you have BASE FUEL which is the preprogrammed best fuel amount for each condition. FUEL TRIM is the result of when the o2 sensor analyzes how rich or lean the car was, then adjusts the fuel trim to compensate as needed. Most cars set a trouble code around +/-25% fuel trim. You really need look at datastream on a scantool and determine if BANK 2 is also lean and just not quite at code level (IE - Bank 1 is at 25% and set a code, Bank 2 is at 22% and did not). In this case, tream it as a problem that affects ALL CYLINDERS instead of a bank.
Now that the bank thing is settled, lets presume you have a 4 cylinder. As said before, vacuum leaks are a common cause and should be checked early on. There are many ways to do this, but the cheapest and easiest is open the hood and listen for the air whistling/sucking sound and follow it. Doesnt always work, but you may get lucky.
Posted on Sep 12, 2009
I would check the O2 sensor, and if it checks bad, replace it, and clear the trouble codes. If the light comes back on, you may need to check further. .
Posted on Oct 28, 2009
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