DEF Quality Poor Message

[JohnnyR]

2012 K3500 Dually, 58K miles

Poor quality DEF message showed up a few days ago. Added fluid but message still there even after going thru a regen for 35 miles. Took it to dealer today but have not heard any news yet. Found nfo online that suggested NOX sensors but but service writer checked for tripped codes and came up blank. Anyone have suggestions? Before i added the 2.5 gallons couple of days ago, last DEF fill was about 3 months ago at a station that had a DEF pump so i filled tank. Worked fine for 3 months so I am doubtful that DEF caused the problem. But I don't know for sure.

[Kennedy]

Pretty common message. System is not smart enough to know what is going on other than NOX levels are not coming down as expected so it blames DEF quality. Could be NOX sensor related or DEF delivery related or bad quality DEF.

The DEF system function and associated headaches can be eliminated while still retaining the DPF and all componentry intact.

[JohnnyR]

Ok, here was fix by dealer. Diagnosed a faulty EGR cooler bypass valve, and added about a qt of coolant. Hopefully the lost coolant went out the exhaust and not into crankcase. Seems fixed for time being.

[cowboywildbill]

At least you have the 100,000 mile power train warranty just in case antifreeze did get into the crankcase and wipes a bearing.
I would think if a quart or so made it into the oil that it would make the oil look a little milky.
But there is a lot of oil in these engines. So who knows.
Maybe it wouldn't hurt to do an oil change just for peace of mind. It's good they found it out the problem quickly.
We had the same message on our 2011 Dually, but the dealer did a re-flash or relearn on the ECM and it solved our problem.
Although when the message "DEF quality poor" appeared my wife asked whats that mean ?
I told her that it was telling her that her hearing aid wasn't working properly.
I won't do that again. !