DEF error and reduced speed

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Apr 17, 2025 | 10:58 AM

Mike Bartlett

Thread Starter

Tuned

Joined: May 2010

Posts: 499

Likes: 132

From: Pleasanton, CA

DEF error and reduced speed

Hi All,

I posted this in he 2015 forum but didn’t get a whole lot of traction so I thought perhaps you all may have some ideas?

Thank you,

Mike

—————————————————————-

This is on my son’s truck a 2015 F250 6.7l 4WD with 139k-miles.

About 4-days ago my son’s truck popped up this warning on his dash cluster.
”In 50-miles speed limited to 50-mph” also “exhaust fluid system fault”. These two messages came up together on the cluster.
Checked for codes he has a 207F code “Generic reductant quality performance”

His DEF tank was below half so he added a jug, 2.5 gal, but no change. His fuel warning light is on meaning low of fuel not sure if anything is related to that? He has about 15-miles to the 50-mph limiting so we haven’t added fuel yet.

*fuel filters are at 15k-miles so those need changing.

Thoughts on this…wondering where to start?

Apr 17, 2025 | 11:41 AM

Ltngdrvr

Lead Driver

Joined: Nov 2005

Posts: 8,477

Likes: 4,973

Code would be P207F, and is that the only code showing? Usually would have more than just that one code.

Here's the best run down on that code I have seen...

Quote:

The P207F is a somewhat difficult code to diagnose. It is defined as "Reductant Quality Performance" but to be more accurate it means that there is insufficient NOx reduction from the SCR catalyst. If there are other codes in the system it is usually required to address those before attempting to diagnose a P207F. There a several possibilities:

Poor reductant quality
Exhaust gas recirculation (EGR) cooler restriction
Damaged SCR system components
Damaged SCR catalyst
Biased NOx sensor

The Exhaust Aftertreatment system and the EGR system rely heavily on sensors therefore any air management sensors such as the MAF and MAP can also be suspect. On a 2012 6.7L there is not upstream NOx sensor to monitor what is going into the catalyst therefore the EGR must be looked at. To add to the list of possibilities contamination of the catalysts will damage them. Oil from the engine or the turbocharger and coolant from the engine and even over fueling can damage the catalysts. Unfortunately, there is no silver bullet to diagnosing and correcting the cause for this code. I will only add that I have replaced MANY catalyst assemblies for this concern. Diagnosing this code is still difficult for many dealership technicians and even more so in the private shops... as for the shade tree guys... good luck. With that said your dealership service department is still your best bet.

Apr 17, 2025 | 12:19 PM

Mike Bartlett

Thread Starter

Tuned

Joined: May 2010

Posts: 499

Likes: 132

From: Pleasanton, CA

Yes the only code was 207F, but I’ll double check to be sure.

Sounds like a tough one to determine root cause, ugh!

Thank you,

Mike

Apr 17, 2025 | 01:45 PM

jimzpsd

Cargo Master

Joined: Feb 2017

Posts: 2,435

Likes: 732

From: Wisconsin

From what I have read...if its low on DEF and you fill it up, it takes a few start up cycles to get the proper level to register with the PCM and not just the gauge. Hopefully it will clear itself out and be fine.