User Tag List

Reply
 
Thread Tools Rate Thread Display Modes
Old 12-06-2014, 09:35 PM #1
psraff's Avatar
psraff psraff is offline
Senior Member
 
Join Date: Aug 2008
Location: Arizona
Age: 51
Posts: 1,163
psraff is on a distinguished road
psraff psraff is offline
Senior Member
psraff's Avatar
 
Join Date: Aug 2008
Location: Arizona
Age: 51
Posts: 1,163
psraff is on a distinguished road
Looking for P0172 writeup

Hey guys... I've started throwing the famous P0172 Error and even though my Scangauge will clear it, it keeps returning every couple of days so I know it's not a freak thing.

I've been searching for days on info and I'm hoping to find a good write up explaining the who's and what's on this error. As we all know, multiple pieces could cause this to happen, and even multiple different combinations of them as well making this very hard to track down.

Is there a write up here, or on another thread that anyone knows about that has a good starting point (most common cause, or most obvious cause) so I'm not running around in circles and spending money on wasted parts? Besides poor fuel mileage, I can't see any difference in the truck running.

Thanks everyone!!!
__________________
AK to AZYota's '99 Build Thread
psraff is offline   Reply With QuoteReply With Quote
Old 03-05-2016, 02:45 PM #2
ferkkila ferkkila is offline
Junior Member
 
Join Date: Mar 2016
Location: Redmond, WA
Posts: 1
ferkkila is on a distinguished road
ferkkila ferkkila is offline
Junior Member
 
Join Date: Mar 2016
Location: Redmond, WA
Posts: 1
ferkkila is on a distinguished road
P0172

This error code was driving me crazy too on my 1999 4runner. The code was very intermittent and didn't really seem to be affecting the way it ran at all. I could drive 200 miles and not see the code then shortly after I start it I would see the code again. I kept my tool to clear the code in the car because the CEL always drives me crazy. I did find that after I cleaned the MAF sensor it would seem to go longer without seeing the code. I finally broke down and bought a $25 Chinese MAF sensor just to see what it would do. I am happy to say I have not seen the code since I replaced the part. I don't know how long this cheap Chinese sensor will last but right now it's working fine and no more CEL. I was also looking high and low for an answer to this issue. Hope this helps.
ferkkila is offline   Reply With QuoteReply With Quote
Old 02-06-2021, 08:20 PM #3
TucsonMike TucsonMike is offline
Member
 
Join Date: Feb 2021
Location: Tucson
Posts: 56
TucsonMike is on a distinguished road
TucsonMike TucsonMike is offline
Member
 
Join Date: Feb 2021
Location: Tucson
Posts: 56
TucsonMike is on a distinguished road
p0172 question

Sorry to revive an old thread but had to sign up again due to inactivity. I do have a 4runner, but my issue is with my Sequoia and since this forum is so helpful I'm hoping someone can help me out. Recently my sequoia has been throwing the PO172. The vehicle has over 200k and still has the original 02 sensors (I know they should be changed due to mileage, but was waiting for 02 specific code to come up). I don't want to throw money at it but was wondering if this is the issue. The MAF has been cleaned (new air filter as well) a while back and I could clean that again.

I do have scanner and have the following info: This was taken at idle approx 700rpm with engine warmed up. Hopefully this info. can help determine if I do have an issue with the 02 or not.

02B1S1 voltage 3.263, 02B2S1 voltage 3.270, O2B1S2 voltage .680, O2B2S2 voltage .740.

Short Fuel Trim bank2 -2.3%, Long Fuel Trim bank2 -25.8%

Short Fuel Trim bank1 -.8%, Long Fuel Trim bank1 -28.1%

Also add the car runs fine. I don't detect black smoke or engine miss. If it wasn't for this code popping up, I wouldn't know anything is wrong with the vehicle.

Appreciate if someone can provide any suggestions.

Thanks

MikeM
TucsonMike is offline   Reply With QuoteReply With Quote
Old 02-06-2021, 09:54 PM #4
T.Tech T.Tech is offline
Member
 
Join Date: Apr 2017
Location: California
Age: 35
Posts: 44
T.Tech is on a distinguished road
T.Tech T.Tech is offline
Member
 
Join Date: Apr 2017
Location: California
Age: 35
Posts: 44
T.Tech is on a distinguished road
If you lean out the mixture by disconnecting a vacuum line, possibly the one for the purge vsv, you should see sensor 1s be about 3.8 v or higher and sensor 2s be close to 0 if they are sensors most likely not the cause.
T.Tech is offline   Reply With QuoteReply With Quote
Old 02-06-2021, 11:16 PM #5
LittleCaesar's Avatar
LittleCaesar LittleCaesar is offline
Elite Member
 
Join Date: May 2011
Location: OBX, NC and Obamaville
Posts: 6,801
LittleCaesar is just really nice LittleCaesar is just really nice LittleCaesar is just really nice LittleCaesar is just really nice
LittleCaesar LittleCaesar is offline
Elite Member
LittleCaesar's Avatar
 
Join Date: May 2011
Location: OBX, NC and Obamaville
Posts: 6,801
LittleCaesar is just really nice LittleCaesar is just really nice LittleCaesar is just really nice LittleCaesar is just really nice
Quote:
Originally Posted by TucsonMike View Post
Sorry to revive an old thread but had to sign up again due to inactivity. I do have a 4runner, but my issue is with my Sequoia and since this forum is so helpful I'm hoping someone can help me out. Recently my sequoia has been throwing the PO172. The vehicle has over 200k and still has the original 02 sensors (I know they should be changed due to mileage, but was waiting for 02 specific code to come up). I don't want to throw money at it but was wondering if this is the issue. The MAF has been cleaned (new air filter as well) a while back and I could clean that again.

I do have scanner and have the following info: This was taken at idle approx 700rpm with engine warmed up. Hopefully this info. can help determine if I do have an issue with the 02 or not.

02B1S1 voltage 3.263, 02B2S1 voltage 3.270, O2B1S2 voltage .680, O2B2S2 voltage .740.

Short Fuel Trim bank2 -2.3%, Long Fuel Trim bank2 -25.8%

Short Fuel Trim bank1 -.8%, Long Fuel Trim bank1 -28.1%

Also add the car runs fine. I don't detect black smoke or engine miss. If it wasn't for this code popping up, I wouldn't know anything is wrong with the vehicle.

Appreciate if someone can provide any suggestions.

Thanks

MikeM
Mike,

Given your long term trim numbers are negative, it indicates that your 2UZ is running rich.

How many O2 sensors does your Sequoia have?

To rule out a vacuum leak, at least most of the time, warm up the Sequoia to operating temp, then rev the engine to around 2000 rpms and check those long term fuel trim values. If they decrease towards zero, then it usually indicates that a vacuum leak exists.

Ever clean the MAF?
LittleCaesar is offline   Reply With QuoteReply With Quote
Old 02-06-2021, 11:33 PM #6
TucsonMike TucsonMike is offline
Member
 
Join Date: Feb 2021
Location: Tucson
Posts: 56
TucsonMike is on a distinguished road
TucsonMike TucsonMike is offline
Member
 
Join Date: Feb 2021
Location: Tucson
Posts: 56
TucsonMike is on a distinguished road
Thanks for the responses guys. I did notice when I rev it up to 2500rpm the long term values I believe decrease slightly but don't recall what those values were. I'll check it again tomorrow. It has 4 total. I have cleaned the MAF about a year or so ago. Will have to verify when.

I'll pull a vacuum hose off and see what happens to those readings

Thanks again

MikeM
TucsonMike is offline   Reply With QuoteReply With Quote
Old 02-07-2021, 12:10 AM #7
TucsonMike TucsonMike is offline
Member
 
Join Date: Feb 2021
Location: Tucson
Posts: 56
TucsonMike is on a distinguished road
TucsonMike TucsonMike is offline
Member
 
Join Date: Feb 2021
Location: Tucson
Posts: 56
TucsonMike is on a distinguished road
At 2000 RPM long fuel trims dropped down to -15.6 for both banks. As I raved it higher they continued to drop some. Does that indicate possible vacuum leak? MAF was cleaned less than 10k miles ago

Thanks
TucsonMike is offline   Reply With QuoteReply With Quote
Old 02-07-2021, 07:27 AM #8
LittleCaesar's Avatar
LittleCaesar LittleCaesar is offline
Elite Member
 
Join Date: May 2011
Location: OBX, NC and Obamaville
Posts: 6,801
LittleCaesar is just really nice LittleCaesar is just really nice LittleCaesar is just really nice LittleCaesar is just really nice
LittleCaesar LittleCaesar is offline
Elite Member
LittleCaesar's Avatar
 
Join Date: May 2011
Location: OBX, NC and Obamaville
Posts: 6,801
LittleCaesar is just really nice LittleCaesar is just really nice LittleCaesar is just really nice LittleCaesar is just really nice
Post

Quote:
Originally Posted by TucsonMike View Post
At 2000 RPM long fuel trims dropped down to -15.6 for both banks. As I raved it higher they continued to drop some. Does that indicate possible vacuum leak? MAF was cleaned less than 10k miles ago

Thanks
While you possibly have a vacuum leak, it isn’t large enough to trip the money light. Usually, but not always, if you have one present those long term numbers would be close to zero while reving the engine to around 2000 rpms.

When warmed up what is your MAF value at idle in g/s?
LittleCaesar is offline   Reply With QuoteReply With Quote
Old 02-07-2021, 10:20 AM #9
Bad Luck Bad Luck is offline
Senior Member
 
Join Date: Feb 2019
Location: Hot Springs, AR
Posts: 4,410
Real Name: Patrick
Bad Luck has a reputation beyond repute Bad Luck has a reputation beyond repute Bad Luck has a reputation beyond repute Bad Luck has a reputation beyond repute Bad Luck has a reputation beyond repute Bad Luck has a reputation beyond repute Bad Luck has a reputation beyond repute Bad Luck has a reputation beyond repute Bad Luck has a reputation beyond repute Bad Luck has a reputation beyond repute Bad Luck has a reputation beyond repute
Bad Luck Bad Luck is offline
Senior Member
 
Join Date: Feb 2019
Location: Hot Springs, AR
Posts: 4,410
Real Name: Patrick
Bad Luck has a reputation beyond repute Bad Luck has a reputation beyond repute Bad Luck has a reputation beyond repute Bad Luck has a reputation beyond repute Bad Luck has a reputation beyond repute Bad Luck has a reputation beyond repute Bad Luck has a reputation beyond repute Bad Luck has a reputation beyond repute Bad Luck has a reputation beyond repute Bad Luck has a reputation beyond repute Bad Luck has a reputation beyond repute
Vacuum leaks 99 percent of the time cause the vehicle to run lean and your fuel trim values to be positive. I would check your spark plugs condition. Toyota oxygen sensors seem to last around 200k so I would also recommend replacing the upstream oxygen sensor. The downstream oxygen sensor is mainly used to monitor catalytic converter efficiency. Since both banks are running rich I wouldn’t suspect coolant in the cylinders or a leaky injector.

Does the 2UZ have an EGR system? A stuck open EGR valve can cause a false O2 reading.
__________________
2000 SR5 V6 Manual 4WD https://www.toyota-4runner.org/3rd-g...biography.html
2000 Limited V6 Auto E-Locker Sold 3/2022
Bad Luck is offline   Reply With QuoteReply With Quote
Old 02-07-2021, 04:13 PM #10
TucsonMike TucsonMike is offline
Member
 
Join Date: Feb 2021
Location: Tucson
Posts: 56
TucsonMike is on a distinguished road
TucsonMike TucsonMike is offline
Member
 
Join Date: Feb 2021
Location: Tucson
Posts: 56
TucsonMike is on a distinguished road
At idle MAF reads 4.53 g/s at 2500RPM 16 40g/s Appears to be the correct range from what I've read. Also new air filter less than 5000miles ago. From what I've read I dont think motor has a EGR. Could fuel pressure regulate be bad?
TucsonMike is offline   Reply With QuoteReply With Quote
Old 02-07-2021, 07:37 PM #11
LittleCaesar's Avatar
LittleCaesar LittleCaesar is offline
Elite Member
 
Join Date: May 2011
Location: OBX, NC and Obamaville
Posts: 6,801
LittleCaesar is just really nice LittleCaesar is just really nice LittleCaesar is just really nice LittleCaesar is just really nice
LittleCaesar LittleCaesar is offline
Elite Member
LittleCaesar's Avatar
 
Join Date: May 2011
Location: OBX, NC and Obamaville
Posts: 6,801
LittleCaesar is just really nice LittleCaesar is just really nice LittleCaesar is just really nice LittleCaesar is just really nice
Those MAF numbers are right to spec, no problem there.

I don’t if you can read the fuel rail pressure for the 2uz through the ECM or a pressure gauge is needed like for the 5vz.

From here, if I were in your shoes, I would look at the voltages values and the switching of the 02 sensors in graph form, to see if there are any anomalies. Then clear the code(s) and wait for the money light to come back on. Then take a look at the Freeze Frame data, to see which of of the data values is out of spec.

Usually when I have dealt with PO 171 and 172 codes, and the car/truck seems to run OK to well, I usually suspect the oxygen sensors have become lazy. It happens with time and mileage.
LittleCaesar is offline   Reply With QuoteReply With Quote
Old 02-07-2021, 08:12 PM #12
TucsonMike TucsonMike is offline
Member
 
Join Date: Feb 2021
Location: Tucson
Posts: 56
TucsonMike is on a distinguished road
TucsonMike TucsonMike is offline
Member
 
Join Date: Feb 2021
Location: Tucson
Posts: 56
TucsonMike is on a distinguished road
Thanks for the suggestions. I'll see what my scanner can do and how much of a pain it is to check fuel pressure. Since car 05 model with 220k on original 02 and fuel pump it certainly can be those. If 02 aren't too terrible to change out probably not bad idea to replace them anyway due to age and mileage. Appreciate everyone taking time to respond. I'll follow up once I get this thing fixed
TucsonMike is offline   Reply With QuoteReply With Quote
Old 03-06-2021, 04:49 PM #13
RoxToy00 RoxToy00 is offline
Junior Member
 
Join Date: Jan 2021
Location: clearwater, FL
Posts: 25
RoxToy00 is on a distinguished road
RoxToy00 RoxToy00 is offline
Junior Member
 
Join Date: Jan 2021
Location: clearwater, FL
Posts: 25
RoxToy00 is on a distinguished road
Hey Mike, similar problem, ever finally resolve yours? My '00 4runner 2wd v6 auto with 240k miles started running ruff when accelerating, threw P0301 code (cyl. 1 miss), replaced all 3 coil pacs, all wires, 6 plugs, 6 injectors (injector in cyl. 1 came out in two pieces, literally), and ran great for 10 min, then CEL back on, idle never dropped from 1200, throwing P0172 code (sys too rich bank 1 - which is bank 1, dr or pass?). I let it sit overnite, again drove around the block, CEL stayed on, parked and plugged in a CAN OBD2 little red scanner and pulled the following information:
DICFR2F P0172 and CEL
FUEL SYS 1 CL
FUEL SYS 2 NA
LOAD PCT 18.4

ETC 178
SHRT FT1 -20.3
LONG FT1 -19.5
RPM 795
VSS 21
IAT 86

MIL STAT OFF
MISFIRE MON OK
FUEL SYS MON OK
COMP COMPON OK
CAT MON INC
HTD CAT NA
EVAP SYS MON INC
SEC AIR SYS NA
A/C REFRIG MON NA
OXY SEN MON INC
OXY SYS HTR OK
EGR SYS NA

Then i cleared the codes, CEL went off, drove again around the block a couple time, and no CEL, and no codes, and 790 idle. I am a believer in Toyota greatness, but come on, a self-repairing car? Any ideas? And what does a flashing CEL mean? receiving codes, or what?
RoxToy00 is offline   Reply With QuoteReply With Quote
Old 03-06-2021, 05:06 PM #14
spartacus's Avatar
spartacus spartacus is offline
Senior Member
 
Join Date: Mar 2010
Location: denver
Posts: 3,010
spartacus has much to be proud of spartacus has much to be proud of spartacus has much to be proud of spartacus has much to be proud of spartacus has much to be proud of spartacus has much to be proud of spartacus has much to be proud of spartacus has much to be proud of spartacus has much to be proud of
spartacus spartacus is offline
Senior Member
spartacus's Avatar
 
Join Date: Mar 2010
Location: denver
Posts: 3,010
spartacus has much to be proud of spartacus has much to be proud of spartacus has much to be proud of spartacus has much to be proud of spartacus has much to be proud of spartacus has much to be proud of spartacus has much to be proud of spartacus has much to be proud of spartacus has much to be proud of
flashing cel mostly means unburned fuel, misfire. Bank one is on passenger side.

Last edited by spartacus; 03-06-2021 at 05:11 PM.
spartacus is offline   Reply With QuoteReply With Quote
Old 03-07-2021, 05:00 PM #15
TucsonMike TucsonMike is offline
Member
 
Join Date: Feb 2021
Location: Tucson
Posts: 56
TucsonMike is on a distinguished road
TucsonMike TucsonMike is offline
Member
 
Join Date: Feb 2021
Location: Tucson
Posts: 56
TucsonMike is on a distinguished road
I haven't fixed mine but since the check engine light hasn't come on in awhile I'm going to wait until it comes on more constantly
TucsonMike is offline   Reply With QuoteReply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
P0172 , + stalling at the lights...any other idea? djtc 3rd gen T4Rs 48 03-06-2021 04:18 PM
CB install writeup Laubage 5th gen T4Rs 36 04-08-2020 02:53 PM
New girl, need advice on CEL- P0172, P1133 MtnChick 3rd gen T4Rs 14 09-07-2013 12:06 PM
p0172 Willhickey 3rd gen T4Rs 0 07-24-2013 08:26 PM
CEL...p0172 and another problem 4Runner93 3rd gen T4Rs 10 05-14-2011 07:56 PM

Powered by vBadvanced CMPS v3.2.2

All times are GMT -4. The time now is 10:37 AM.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2024 DragonByte Technologies Ltd.
Feedback Buttons provided by Advanced Post Thanks / Like (Lite) - vBulletin Mods & Addons Copyright © 2024 DragonByte Technologies Ltd.
User Alert System provided by Advanced User Tagging (Lite) - vBulletin Mods & Addons Copyright © 2024 DragonByte Technologies Ltd.
***This site is an unofficial Toyota site, and is not officially endorsed, supported, authorized by or affiliated with Toyota. All company, product, or service names references in this web site are used for identification purposes only and may be trademarks of their respective owners. The Toyota name, marks, designs and logos, as well as Toyota model names, are registered trademarks of Toyota Motor Corporation***Ad Management plugin by RedTyger
 
Copyright © 2020