Ive been battling it since february off and on. Ive spent alot of time over these last few months searching the web and here for a fix but found no one has come up with a solution. Or maybe they did and never updated their thread, or everyone just gave up and lived with it?

My story in a nut shell
2017 F250 6.7 currently at 102k
Whats been done so far: TSB for re mapping, MAF sensor replaced, EGR replaced (MAF 1st then after code came back they said EGR was bad) REplacing the EGR kept it from coming back for several months but then it came back so took it to the shop... their testing protocol couldnt find any issue so the sent it to the ford hotline, they come back with replace all 8 injectors.....
Im waiting on answers to several questions I posed to the service manager as to how they arrived at that 6k solution after I already have $2200 in what has been done to date cause I need some facts that I can agree with before I spend that much money. Hopefully they pulled some data from the engine and can tell me they saw something that tells them they are bad but itd seem to me there is extremely low odds that the MAF, EGR and 8 injectors went bad in 8 months time. Quite a few times the check engine light goes off by itself before I can get to the shop

So thought Id check in here see whats out there for solutions or If I just say F it and ride it out with the chk eng light on lol. Thanks for your time

 

You’ve done the TSB, and that seems to be most of the definitive information.

I get it occasionally, and probably have it now, lamp is on again. It seems to happen to me after I’ve been running reasonably hard and suddenly come to a stop, like a traffic jam. I reset using Forscan and it’s gone until the next time, averaging once every 3k miles. Judging by the problems you’re having I’ll keep on doing it.

 

so they didn’t replace your O2 sensors?

this code is a result of calculations made from o2 sensor data.

https://www.ford-trucks.com/forums/a...0&d=1509326014







also…some folks report faulty map sensor wires or map sensor connector flimsy

 

Yea I think Im prepared to say F it and run it... Its come on and went off on its own several times most recently last night it went off after being on a week or so. How long have you been dealing with it?


Thats a no on an O2 sensor... info Ive seen so far specific to a diesel is that a NOX sensor can cause it. Thanks for the info..... Ill take a look at the MAP sensor wiring

 

A Ford 6.7 diesel P0170 code, which indicates a "Fuel Trim Malfunction (Bank 1)," is calculated by the vehicle's computer by comparing the actual air mass entering the engine (measured by the Mass Airflow Sensor) to the amount of fuel injected, and determining if there is a significant discrepancy between the ideal air-fuel ratio and the actual ratio, signifying a need for fuel trim adjustments to compensate for a rich or lean condition; if the discrepancy exceeds a predetermined threshold, the P0170 code is triggered.

Key points about P0170 calculation:

• Air Mass Sensor Data:
  The primary input for calculating fuel trim is the signal from the Mass Airflow Sensor (MAF), which measures the amount of air entering the engine.
• Fuel Injector Pulse Width:
  The computer also monitors the duration of the fuel injector pulse, which indicates the amount of fuel being injected.
• Fuel Trim Adjustments:
  The ECU continuously adjusts the fuel trim based on the air mass and fuel injected, attempting to maintain the ideal air-fuel ratio.
• Threshold Exceeded:
  If the required fuel trim adjustments become too large to maintain the correct air-fuel ratio, the P0170 code is set, indicating a significant fuel trim malfunction.

Potential causes for a P0170 code:

• Faulty MAF sensor:
  A dirty or malfunctioning MAF sensor can provide inaccurate air mass data, leading to incorrect fuel trim calculations.
• Fuel pressure issues:
  Low fuel pressure can prevent the correct amount of fuel from being delivered to the injectors.
• Fuel injector problems:
  Faulty injectors can cause uneven fuel delivery, leading to a rich or lean condition.
• Vacuum leaks:
  Air leaks in the intake manifold can disrupt the air-fuel ratio.
• Oxygen sensor issues:
  A faulty oxygen sensor can provide incorrect feedback to the ECU, affecting fuel trim adjustments.

Diagnosing P0170:

• Scan tool analysis:
  Use a scan tool to read the P0170 code and review live data from the MAF sensor, oxygen sensors, and fuel pressure to identify potential issues.
• Visual inspection:
  Check for visible signs of damage or leaks in the intake system, fuel lines, and vacuum hoses.
• Component testing:
  Test the MAF sensor, oxygen sensors, fuel pressure regulator, and fuel

 

I got it a year ago and it’s always done it - who knows how long before…

 

NOx info controls DEF flow

O2 info controls fuel air mixture

per google

The purpose of a diesel NOx sensor is to:

A NOx sensor is a key component of a diesel engine’s emissions control system. It monitors the level of nitrogen oxides (NOx) in the exhaust gas1234. If the NOx sensor detects too much NOx gases being emitted, it sends that information to the SCR system, which then adjusts the output to a level that’s compliant with emission regulations1. By doing this, harmful emissions are reduced, and cleaner air is achieved5.


The purpose of a diesel O2 sensor is to:

Measure the amount of oxygen in the exhaust stream and send this information to the engine control module (ECM)1.
Gauge the ratio of fuel-to-air that the engine is receiving by measuring the amount of oxygen in the exhaust and feed this information to the on-board computer known as the Engine Control Unit (ECU)2.
Monitor the exhaust gases that leave the catalytic converter and ensure they are within acceptable levels to help the vehicle run more efficiently3.
Confirm the proper function of the catalytic converter4.
Regulate the ratio of the fuel mixture by flip-flopping between rich and lean mixtures, allowing the catalytic converter to lower emissions5.

 

Here’s some is and box numbers to compare

warmed up engine

37 degrees out

O2 is the first row
nox is the third row

bank1 / bank 2


at idle




at 1000 rpm




at 1500 rpm


at 2000 rpm


at 2500 rpm




vehicle is stationary in all cases above.


For the folks having this trouble code, i would be curious of your O2 bank 1 / bank 2 numbers at different rpms .

 

Thanks Speaker.... Ill have to research where the O2 sensor is a and also question dealer as to if it was part of the pinpoint testing. Im guessing there must be 2?

 

good deep dive video…MAF out of range at 2k rpms

 

Yep... I had seen this video some time ago when all this started but thanks for looking out. Im Still waiting on answers to the questions I posed to the service manager

 

Were you able to solve the P0170 issue? Thanks,

 

Nope. Took it to another private shop that has a decent rep.... he started from scratch with testing for this code on fords diag software found no discrepancies, did a thorough smoke test on the intake system and spent some time driving the truck while looking at engine data in a laptop. Said he doesnt think its injectors all that data looked excellent. Said he thinks he saw NOX data at zero for a brief second. Took it back a few days later when it came back he looked at Data again driving the truck and couldnt see any issues. When it came back again he told me he gives up because its so intermittent it almost impossible to pinpoint what the issue is. Thinking about changing the NOX sensor... its the original one and theres not way to do any testing on it like you can on other items.

 

9 times out of 10 it's a worn fuel check valve letting fuel in the line run back into the tank, it'll throw up the code before you even start experiencing a false start or two and 20-30 seconds of rough idle while the fuel pressure builds back up.