For the longest time ive had this code thrown and cant figure out whats causing it. I had P0134 as well and replaced the front 02 sensor so that codes gone now. I thought that might be what was causing the code to be thrown but its still not gone. From searching the site and see who else has thrown this code I dont have any vacuum leaks and my MAF sensor is clean. the BOV is recirculated. Injectors are tightened all the way. can it be somthing else?

 

nobody?

 

so which code is causing u problems the 134 or 172?

 

I used to throw that code when i upgraded my injectors without scaling them properly. Lean condition i believe.

 

i had the 0172 from a tiny tear in my intercooler pipe that was hard to find

 

Getting the same exact code myself for 4 weeks now. Performed similar troubleshooting with no luck. Taking her apart again to check for tear or loose intercooling piping.

 

ya im gonna have another boost leak test to double check

 

Anything after Buscher Stage 4 means you have upgraded fuel injectors....have you checked your furl trims lately?

I am actually in the middle of tuning an Evo for a buddy of mine that has this code after installing RC 1000cc injectors. His idle fuel trim is at -3/3 but his short and middle trims are at -13 each...you can literally see the fuel coming out of the exhaust....gotta get his cc and latency settings changed to compensate....


From obd-codes.com...

P0172 OBD-II Trouble Code
Technical Description

System Too Rich (Bank 1)
What does that mean?

Basically this means that an oxygen sensor in bank 1 detected a rich condition (too little oxygen in the exhaust). On V6/V8/V10 engines, Bank 1 is the side of the engine that has cylinder #1.

Note: This DTC is very similar to P0175, and in fact your vehicle may show both codes at the same time.
Symptoms

You will more than likely not notice any drivability problems, although there may be symptoms such as a misfire.

Causes

A code P0172 may mean that one or more of the following has happened:

* The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters (K&N, etc.) can cause the MAF to become dirty if the filter is over-oiled
* There could be a vacuum leak.
* There could be a fuel pressure or delivery problem

Possible Solutions

Possible solutions include:

* Inspect all vacuum and PCV hoses, replace if necessary
* Cleanthe MAF sensor. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
* Inspect fuel lines for cracks, leaks, or pinches
* Check the fuel pressure at the fuel rail
* Check the fuel injectors, they may be dirty. Use fuel injector cleaner or get them professionally cleaned/replaced.
* Check for an exhaust leak before the first oxygen sensor (this is unlikely to cause the problem, but it is possible)

 

A yes, system too rich, my bad

 

the exhaust leak i had when i got tuned last is what is causing the code to be thrown. just came back from replacing my HKS filter with a new one and now i got p0134!

 

I use to get the 172 until Jestr tuned my injectors to what it's suppose to be. I had got my injectors from an unknown source. I couldn't tell him what brand they where. The car idled like I had cams. So he actually went through a list of injectors tell he put in the right one, and bam! The car's idle was back to normal, and the 172 codes never came back. So there you go........I believe it's a System too rich code (Bank 1)

 

Ya i think its from when i got tuned last i had a bad exhaust leak where the downpipe met the o2 housing so that threw the AFRs off on the dyno making it seem like it was running lean

 

I tried to go for inspection today and was turned down cuz my advans were bald....I was kinda complaining at the guy but i'm glad he turned me down anyway since I am throwing a P0172 code w/o knowing it.....

How can I resolve it? I'm thinking I will need to put my stock fuel pump back in .....other than that I'm running on the stock ECU, MAF, and injectors ......

This is becoming a pain in the butt....

 

If it helps, here is the specific info from the evo manual:

DTC P0172: SYSTEM TOO RICH
.
System too Rich Circuit
• Refer to, DTC P0201 − P0204 Injector Circuit Malfunction P.13A-267.
.
CIRCUIT OPERATION
• Refer to, DTC P0201 − P0204 Injector Circuit Malfunction P.13A-267.
.
TECHNICAL DESCRIPTION
• If a malfunction occurs in the fuel system, the fuel trim value becomes too small.
• The ECM checks whether the fuel trim value is within a specified range.
.
DTC SET CONDITIONS
Check Condition 1
• Under the closed loop air/fuel ratio control.
• Engine coolant temperature is higher than 77°C (171°F).
• Volume airflow sensor output frequency is 56 Hz or more.
Judgment Criteria
• Long-term fuel trim has continued to be lower than −12.5 percent for 5 seconds.
or
• Short-term fuel trim has continued to be lower than −10 percent for 5 seconds.

Check Condition 2
• Under the closed loop air/fuel ratio control.
• Engine coolant temperature is higher than 77°C (171°F).
• Volume airflow sensor output frequency is 56 Hz or less.
Judgment Criteria
• Long-term fuel trim has continued to be lower than −12.5 percent for 5 seconds.
or
• Short-term fuel trim has continued to be lower than −15.0 percent for 5 seconds.

Check Condition 3
• Engine coolant temperature is higher than 77°C (171°F).
• Under the closed loop air/fuel ratio control.
Judgment Criteria
• Long-term fuel trim has continued to be −12.5 percent for 5 seconds.
or
• Short-term fuel trim has continued to be −25.0 percent for 5 seconds.
.
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are: )
• Volume airflow sensor failed.
• Injector failed.
• Incorrect fuel pressure.
• Engine coolant temperature sensor failed.
• Intake air temperature sensor failed.
• Barometric pressure sensor failed.
• Harness damage in injector circuit, or connector damage.
• ECM failed.

 

Injector needs to be scaled and voltage latency needs to be adjusted to get the STFT correct.