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Toyota Check Engine Light on and Error Code is P0171 - What needs to be fixed? - Finally Fixed see p

Post in 'DIY and General non-hearth advice' started by Don2222, Mar 24, 2011.

  1. Don2222

    Don2222 Minister of Fire

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    Feb 1, 2010
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    Salem NH
    Hello

    Well the vacuum booster part was ordered. Still waiting for it to come in.

    So in summary the best way to fix this issue is by starting with the cheapest parts first.
    Toyota CEL Check Engine Light Error Code P0171

    Here is the way I should have gone.

    1. Engine Vacuum Lines

    a. Check or replace the two vacuum lines that go from the engine to the vacuum reserve canister under the battery.
    You can use American 5/32 line but if your can get the smaller outside diameter foreign line, the engine holding clips will still work and keep the line away from the hot motor.

    b. Check or replace the vacuum booster line from the engine to the vaccuum booster behind the master cylnder.
    American 3/8 Vacuum booster hose will work fine.

    c. Check all other engine vacuum lines but the above two are the common cause.

    2. MAF -Mass Air Flow Sensor.
    Make sure you have the additional error codes below. Use OEM because a refurbished part will not give the performance!
    P0100 - Air Flow Meter
    P0110 - Air Flow Malfunction
    Toyota OEM MAV part is $231.00 and makes the car perform like new, but the Re-furbished MAV for $70.00 will give more trouble!

    3. Flex Line Exhaust Leak before the down stream O2 Sensor.
    Should also get a P0420 error code to turn the light on.
    Aftermarket part is $50.00 while the OEM Toyota part is part of the catalytic converter and costs $2,000.00
    It must be done anyway for inspection if there is an exhaust leak here. The aftermarket works fine.

    4. Low Fuel Pressure
    Replace Toyata inline fuel filter on the driver's side inside front fender near the battery.
    Toyota style replacement $65.00 at auto parts store. You can probably install an inexpensive inline real cheap here!
    This is not so easy since the metal fuel line screws right into the filter!
    The easiest way is to cut the fuel line and remove the other side which is a rubber hose.
    Install the new Fuel filter by unscrewing the old line from the old filter and screwing it onto the new filter.
    Then add a rubber fuel line to connect the severed ends together!

    5. Misfire
    Replace all spark plugs and wires. The car will run better if they are old anyway.
    My wires crumbled from being old and brittle!

    6. Vacuum Booster Behind the Master Brake Cylinder.
    Before replacing this part there are 2 simple tests to make sure it is bad.
    A. When driving and stepping on the brakes you will hear a hiss sound of the leaking air.
    B. After turning the key off the brake Pedal will not press down easily one last time!
    Compare with a working car and you will feel the difference!
    Aftermarket booster is $500.00 and made to last a long time OEM Toyota is $900.00 and obviously does not last long!

    7. Replace O2 Sensors. You also get better gas mileage! After market O2 sensors made for Toyota usually work.
    Replace the 2 upstream sensors on the exhaust manifolds
    Replace the 1 downstream O2 sensor after the catalytic converter. (You can use a Dummy Sensor here if you can find one!)
    Nice removal tool that works with an Air Chisel!
    >> http://www.thetoolwarehouse.net/p-3128-lisle-43900.aspx

    Helpful Sponsor Ads!





  2. Don2222

    Don2222 Minister of Fire

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    Hello

    Well, I got a used Toyota Vacuum Booster for $170.00 from Arizona and had it installed today. No more hissing when braking! We will see if that fixes it?
    A little cheaper than $900.00 for the Brand New OEM Toyota part!

    Attached Files:

  3. Don2222

    Don2222 Minister of Fire

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    Hello

    Well the new vacuum booster finally fixed the P0171 code.

    Interesting because I took it on my newly developed Drive Cycle after the booster was installed.

    New Drive Cycle for Toyota

    With the gas tank between 1/2 and 3/4 full to change the Monitors for emissions in the car’s computer from “Not Ready†to “Readyâ€

    Drive the car 25 miles half highway and half city (stop & go) and while on the highway include a minimum speed of 55 mph for a min of 3-5 mins and then coast to a stop on the side of the road and keep engine idling for 3-5 mins without breaking and then back up to 55 MPH for 3 - 5 mins.

    When I took it back to the shop we put the Genesis Code Scanner on the car and found only 1 Monitor - EVAP system was not ready.

    Now the EPA standard states it is OK to have 1 monitor "Not Ready" for 2001 and newer cars and 2 Monitors "Not Ready" for cars 1996-2000. So having a 1999 I was all set. Sure enough< I got my inspection sticker. CASE CLOSED.

    See pics below of BAD VACUUM BOOSTER

    Attached Files:

  4. jlove1974

    jlove1974 Member

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    When I had P0171 and P0174 (it's a V8) on our 2003 Suburban, I checked for vacuum leaks. The fuel pump had been changed 13 months beforehand, so I assumed it was an air leak....
    WRONG. After replacing various fuel and vacuum parts (and using a AZ MAF sensor w/ a new delco sticker on it), it turned out to be the budget Airtex pump only putting out 20psi (should be around 40-45 psi) fuel pressure.
    I put a Delco pump on it and VOILA no more lean code.

    OBD-II sucks, IMO. it's too darn picky LOL. The truck ran OK, but I couldn't get it inspected for a month until I fixed it
  5. Don2222

    Don2222 Minister of Fire

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    Hi jlove

    Thanks for the info, I replaced the gas filter but that did not fix it.

    Well glad our ordeals are over !!!
  6. jlove1974

    jlove1974 Member

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    I guess so. My next vehicle acquisition is a 2000 Honda Odyssey (to relieve the pain at the pump the 'burb is currently causing!) with 178K miles.
    It has a code on the dash which says the transmission is basically dead. Good thing I am only paying $2000 for it. And the tranny w/ warranty is $1K.

    We'll see if the Honda is any more reliable than the Chevy. Somehow, I doubt it. After their numerous transmission problems in these vans, I would
    only buy one with a rebuilt transmission w/ warranty. Oh and a timing belt/water pump job done recently.

    Don, I would recommend if you don't already have one of these in your toolkit:

    http://www.harborfreight.com/fuel-injection-pump-tester-92699.html it's worth it's price many times over for fuel injected cars.

    Also the cheap CAN OBD-II tester I use (was $39 on sale) http://www.harborfreight.com/can-obdii-code-reader-with-multilingual-menu-98568.html
  7. TMonter

    TMonter Minister of Fire

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    I have an odyssey and can speak to the transmission issue.

    First be very careful with a transmission that only costs $1000, that price is very suspect. My total rebuild on my 2001 Odyssey cost me about $2800 with removal/replacement a cooler install and a inline filter addition.

    The biggest problem with Odyssey's has been the trans fluid they use. It's not synthetic so it has a tendency to overheat easily and burn the fluid. I recommend a full synthetic fluid like Amsoil or equivalent. If you want to start a new thread I can give some more suggestions as I've gone through this whole transmission issue in detail.

    Average transmission life on an odyssey with a good rebuild and regular maintenance seems to be about 175K+ miles.
  8. jlove1974

    jlove1974 Member

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    The price is not including labor. It'll be around $1500 w/ full synthetic fluid and labor (a friend who is a ATRA certified trans tech).
    He rebuilt an electronic 4wd transfer case for us last spring that was better than factory new when I got it back. I did the install on that one.

    I didn't feel like pulling the tranny w/o a lift so I figured $500 for labor was a steal....compared to what Honda charges.

    I'm planning on putting another 100-150K on this one, hopefully the gas situation will be settled by then (approx. 3 years).

    I will be doing the timing belt/water pump myself after I get the van back from the trans rebuild. Looks about like what my mazda KL V6 was, a PITA
  9. TMonter

    TMonter Minister of Fire

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    Make sure you add a good inline filter like a Magnafine and a large transmission cooler. The new transmission also includes a new Torque converter I hope.
  10. Don2222

    Don2222 Minister of Fire

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    Hello

    Well folks, it has been a month now and the MIL (Malfunction Illumination Lamp) Alias CEL (Check Engine Light) is NOT ON !!

    The used Vacuum Booster really fixed it!!
  11. heat seeker

    heat seeker Minister of Fire

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    :) :) :)
  12. Don2222

    Don2222 Minister of Fire

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    Hello

    Well I learned alot from this ordeal. The most important fact is the EPA emissions testing alows 1996 to 2000 cars to have 2 emission system monitors in your car's computer in "Not Ready" status and 2001 cars and above can have 1 emission system monitor in "Not Ready" status and PASS emissions testing. This means if you reset the car's computer by temporarily removing one of the battery terminals. You can see the monitors go to "Ready" status with an inexpensive code checker as you drive the car. So if you have a problem in the evaporator system which is the last monitor to go to "Ready" status, just get the emissions tested after the other monitors are in "Ready" status and you will pass the emissions testing!!! If you have a pre-2001 car then the system before the evaporator system can also be broken and still get a sticker!! Also the drive cycle to get these monitors "Ready" is by driving the car approx 12 miles on the highway and then 12 miles back on a regular stop and go route! Then you will be ready for emissions testing after reseting the car's computer!!

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