AutoCodes – Toyota – P0172 Toyota

P0172 Toyota Code - Fuel Trim System Too Rich Bank 1

Quick Answer

The fuel trim is related to the feedback compensation value, not to the basic injection duration. Common causes include Fuel injector leak or blockage, Faulty Mass Air Flow (MAF) sensor, Faulty Engine Coolant Temperature Sensor. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0172 Toyota indicates Fuel Trim System Too Rich Bank 1.
Common causes: Common causes include Fuel injector leak or blockage, Faulty Mass Air Flow (MAF) sensor, Faulty Engine Coolant Temperature Sensor.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 171,680

How popular is this code, among other codes? High

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Aug 24, 2022

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P0172 Toyota Description

The fuel trim is related to the feedback compensation value, not to the basic injection duration. The fuel trim consists of both short-term and long-term fuel trims.
The short-term fuel trim is fuel compensation that is used to constantly maintain the air-fuel ratio at stoichiometric levels. The signal from the air-fuel ratio sensor indicates whether the air-fuel ratio is rich or lean compared to the stoichiometric ratio. This triggers a reduction in the fuel injection volume if the air-fuel ratio is rich and an increase in the fuel injection volume if lean.
Factors such as individual engine differences, wear over time, and changes in the operating environment cause short-term fuel trim to vary from the central value. The long-term fuel trim, which controls overall fuel compensation, compensates for long-term deviations in the fuel trim from the central value caused by the short-term fuel trim compensation.
Under closed-loop fuel control, fuel injection volumes that deviate from those estimated by the Engine Control Module (ECM) cause changes in the long-term fuel trim compensation value. The long-term fuel trim is adjusted when there are persistent deviations in the short-term fuel trim values. Deviations from the fuel injection volumes estimated by the ECM also affect the average fuel trim learned value, which is a combination of the average short-term fuel trim (fuel feedback compensation value) and the average long-term fuel trim (learned value of the air fuel ratio). If the average fuel trim learned value exceeds the malfunction thresholds, the ECM interprets this as a fault in the fuel system and stores a Diagnostic Trouble Code (DTC).

OBDII Code P0172 Toyota - Fuel Trim System Too Rich Bank 1 - AutoCodes.com — P0172 Toyota Code - Fuel Trim System Too Rich Bank 1

What does this mean?

What are the Possible Causes of the DTC P0172 Toyota?

Fuel injector leak or blockage
Faulty Mass Air Flow (MAF) sensor
Faulty Engine Coolant Temperature Sensor
Faulty Air Fuel Ratio (A/F) Sensor (Front Oxygen Sensor)
Incorrect fuel pressure
Gas leak from exhaust system
Air Fuel Ratio Sensor harness is open or shorted
Air Fuel Ratio Sensor circuit poor electrical connection
Faulty Engine Control Module (ECM)

How to Fix the DTC P0172 Toyota?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0172 Toyota code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P0172 Toyota code?

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Need Help with the Code?

Get the P0172 Toyota code diagnosed by a professional: Find a repair shop in your area

Information for Specific Toyota Models

P0172 1997 Toyota Camry — System Too Rich Bank 1
P0172 1998 Toyota Camry — System Too Rich Bank 1
P0172 1999 Toyota Camry — System Too Rich Bank 1
P0172 2000 Toyota Camry — System Too Rich Bank 1
P0172 2001 Toyota Camry — System Too Rich Bank 1
P0172 2006 Toyota Camry — System Too Rich Bank 1
P0172 2007 Toyota Camry — System Too Rich Bank 1
P0172 2008 Toyota Camry — System Too Rich Bank 1
P0172 2009 Toyota Camry — System Too Rich Bank 1
P0172 2010 Toyota Camry — System Too Rich Bank 1
P0172 2011 Toyota Camry — System Too Rich Bank 1
P0172 2001 Toyota Corolla — System Too Rich Bank 1 3ZZ-FE Engine
P0172 2002 Toyota Corolla — System Too Rich Bank 1 3ZZ-FE Engine
P0172 2003 Toyota Corolla — System Too Rich Bank 1 3ZZ-FE Engine
P0172 2004 Toyota Corolla — System Too Rich Bank 1 3ZZ-FE Engine
P0172 2005 Toyota Corolla — System Too Rich Bank 1 3ZZ-FE Engine
P0172 2006 Toyota Corolla — System Too Rich Bank 1 3ZZ-FE Engine
P0172 2001 Toyota Highlander — System Too Rich Bank 1
P0172 2002 Toyota Highlander — System Too Rich Bank 1
P0172 2003 Toyota Highlander — System Too Rich Bank 1
P0172 2004 Toyota Highlander — System Too Rich Bank 1
P0172 2005 Toyota Highlander — System Too Rich Bank 1
P0172 2006 Toyota Highlander — System Too Rich Bank 1
P0172 2007 Toyota Highlander — System Too Rich Bank 1
P0172 2004 Toyota Prius — System Too Rich Bank 1
P0172 2005 Toyota Prius — System Too Rich Bank 1
P0172 2006 Toyota Prius — System Too Rich Bank 1
P0172 2007 Toyota Prius — System Too Rich Bank 1
P0172 2008 Toyota Prius — System Too Rich Bank 1
P0172 2009 Toyota Prius — System Too Rich Bank 1
P0172 2013 Toyota RAV4 — Fuel Trim System Too Rich Bank 1
P0172 2014 Toyota RAV4 — Fuel Trim System Too Rich Bank 1
P0172 2015 Toyota RAV4 — Fuel Trim System Too Rich Bank 1
P0172 2016 Toyota RAV4 — Fuel Trim System Too Rich Bank 1
P0172 2017 Toyota RAV4 — Fuel Trim System Too Rich Bank 1
P0172 2018 Toyota RAV4 — Fuel Trim System Too Rich Bank 1

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0172 Toyota Code

No Frequently Asked Questions about P0172 Toyota Code found.

Discuss the causes and fixes for P0172 Toyota OBDII Code

Submit a New Comment

Bill
Date: July 13, 2013 at 6:11 am

I did replace MAF sensor and O2 sensor with original new Toyota parts and there is no change in engine running(misfire and excess usage of gas)Please help.Thanks

Reply to Comment
OBDIITech
Date: July 14, 2013 at 12:39 am

What model and year is your Toyota?

Reply to Comment
Jason
Date: October 1, 2014 at 4:26 pm

I have the same problem replaced both and mines a2010 corolla 1.8

Reply to Comment
OBDIITech
Date: October 3, 2014 at 10:45 pm

Check for intake leaks and make sure the Air Filter its clean.

Reply to Comment
barry
Date: October 22, 2015 at 4:57 pm

good afternoon I have a 2006 rav 4 and the engine light, vsc and four wheel drive light came on

Reply to Comment
barry
Date: October 22, 2015 at 5:24 pm

codes for 2006 Toyota rav 4

Reply to Comment
OBDIITech
Date: October 22, 2015 at 5:32 pm

Hello Barry, Are there any more codes, besides de P0172 code? do you have the code numbers? there should be a code for the VSC and 4WD.

Reply to Comment
Jo Cole
Date: May 18, 2016 at 11:34 am

Hi,
I have problem this code after I did following tasks
1) Injector Cleaning
2) Fuel Pump Replace
3) Trottle Cleaning
4) Spark Plug Replace
But engine stalled when idle by suddenly drop rpm. Then this fault code founded. I would be appreciate when you give some useful advices. Thanks You.
With Regards,
JoCole

Reply to Comment
OBDIITech
Date: May 18, 2016 at 9:45 pm

What model and year is your Toyota. Try disconnecting the car battery for about 30 minutes to reset the system. Usually the engine idle speed should rest it self while driving, but sometimes you have to disconnect the car battery.

Reply to Comment
Jo Cole
Date: May 19, 2016 at 1:43 am

Model is Toyota Corolla 2003. I found a solution. This fault happen because 1 pressure pipe in brake survo have air leak.
Okay. I'll do also reset. Thanks you so much.

Reply to Comment
Shervin Hamilton
Date: January 14, 2017 at 1:24 am

What I can do with my toyota corolla 2010 I change the MAF sensor twice an it still showing check engine light I connect it to the scanner reset them an go for a drive an the check light still showing

Reply to Comment
OBDIITech
Date: January 14, 2017 at 2:18 am

The P0171 is not saying exactly that the problem is the MAF, the P0171 code means that there is too much gas in the mixture or not enough air. Is there any other symptom? when was the last time you change the spark plugs?

Reply to Comment
Kevin Seven
Date: April 30, 2017 at 3:24 pm

I have an issue and nobody seems to know what is wrong. I have an imported 2007 Toyota bB. After accidently placing copper plugs instead of iridium I have had terrible performance and fault code p1072 fuel rich bank 1. I've had my cat cleaned, throttle body cleaned, iridium plus placed full service and I'm still having the same issue. I experience loss of acceleration, random stalls, exhaust backfire, black smoke and greater loss of power when air conditioning is switched on. Car runs better in colder environments but once engine heats up it has issues. Please help.

Reply to Comment
OBDIITech
Date: May 1, 2017 at 10:20 pm

All the symptoms point to stuck open fuel injectors. You could try adding a fuel injector cleaner for a couple of weeks or replace the injectors.

Reply to Comment
Estuardo Manzano
Date: May 3, 2017 at 5:18 pm

Hello, I have this problem with my Toyota Corolla 2015
** symptoms:
On inclinations, if I press the gas pedal thoroughly , there it is like if it drowns, if it comes out slow or the car remains stuck ** and throw some black smoke ***
At first I had the code P0101 and P0172 (I fixed the vacuum leak of code P101)
Now I only have code P0172
What has been done:
-and changed spark plugs
-and filters were changed
-and already checked the electrical connections
-the catalytic was already checked
Also fix the vacum leak (I fix it)
I already changed the defective oxygen sensor (I already changed it, unless the one that I put this bad)
I also changed the MAF sensor
please help me

Reply to Comment
OBDIITech
Date: May 4, 2017 at 2:37 am

Is it already out of warranty?
The code means that there is more fuel than air during combustion. The extra fuel is also causing the black smog. Intake leaks should not cause that problem, the most common causes that I have seen are:
- Fuel injector leaking - Injector stuck open and dumping fuel
- Bad MAF sensor signal to ECM
---- Bad signal could be caused by faulty MAF but you already replaced that
---- Bad signal could also be caused by poor ground to the MAF
- Excessive carbon built up in the engine
I suggest starting by using high octane gas and fuel injector cleaner, and check if that improves the engine performance.

Reply to Comment
Estuardo Manzano
Date: May 4, 2017 at 2:46 am

Thank you, I will do your recommendations
Thanks

Reply to Comment
Saud ali shah
Date: February 22, 2018 at 6:30 am

I have same problem in my vitz model 2000. After driving arround 1 or 2 or stuck in bad traffic for hour it giving check engine light. When i check on scanner its giving p0172 code. Can you please advice

Reply to Comment
OBDIITech
Date: February 22, 2018 at 2:36 pm

Unfortunately, there are many thing that could trigger the P0172 code. You could by replacing the engine air filter and cleaning the Mass Air Flow (MAF) sensor.

Reply to Comment
El Especie Corazón
Date: April 6, 2018 at 12:32 am

Hi , I have the same issue. toyota yaris 2012. with p0132 and p0172 ..cleaned throttle body , maf and replace plugs to iridium. runs well when cold, starts to shake once warmed up then stalls. this symptom happened quicker when using ac. not sure if i should replace o2 sensor too aside from your advice to use fuel injector cleaner.

Reply to Comment
OBDIITech
Date: April 6, 2018 at 2:31 am

Use the fuel injector cleaner first for a couple of weeks, before you replace any parts.

Reply to Comment
Joy Mollik
Date: August 30, 2018 at 12:48 am

Hello,I have the same problem,NOAH 2012 With valve matic.Trabol code p0172.I also changed.
Injector assembly
A/F sensor
O2 sensor
MAF sensor
there is no incriment
Otc scaner data list also show that MAF data 3000 rpm 15 gm/sec.
Please advice...

Reply to Comment
Mark Schrader
Date: April 14, 2023 at 2:29 pm

I have a 1999 tacoma, engine code P0172 still on after changed MAF sensor, changed plugs and coils, new injectors, O2 sensor bank 1, new PCV valve, new air filter, fixed a vacuum hose leak. What can it be??

Reply to Comment
OBDIITech
Date: April 14, 2023 at 3:19 pm

Check the fuel pressure to see if it is too high. Fuel pressure should be 33-38 with vacuum on the regulator and 38-44 with no vacuum. If the fuel pressure is high suspect the fuel pressure regulator to be at fault. Make sure the return fuel line is not damaged or restricted.

Reply to Comment
Mark Schrader
Date: April 14, 2023 at 5:15 pm

ok will give it a try! Thank you very much!

Reply to Comment
Mark Schrader
Date: April 15, 2023 at 11:19 pm

I replaced the fuel pressure regulator and still have the engine check light on and the lines are not damaged. Any other ideas? Thanks!

Reply to Comment