2017 NOx 1-1 Module Connector & Water

Keith Browning · July 21, 2017

I had TWO new F550 trucks in with water intrusion of the NOx 1-1 connector. Corroded the terminals in the connector and into the module itself. The trucks had different codes, One with heater circuit fault and the other with communication errors. I did not see anything unusual about the connector or the module that looked damaged that would explain how water was getting in. The only thing that these trucks had in common is they are brand new FDNY ambulances that had not been delivered yet which really should not mean anything but worth mentioning. There is no repair pigtail according the wiring manual on PTS so I ended up replacing the harnesses and modules applying electrical grease strategically, cleared the module tables in the PCM and the codes and sent them on thier way. So if you see any upstream NOx issues inspect that connection really well.

Brad Clayton · July 21, 2017

Like button...engaged.

forddieseldoctor · July 21, 2017

I thought the book says that you are not supposed to grease nox module connectors?

Brad Clayton · July 22, 2017

What the book wants and what the book gets don't always coincide.

Keith Browning · July 22, 2017

I thought the book says that you are not supposed to grease nox module connectors?

Yes, it does and it does not explain WHY therefore it makes little sense. Here is the reason for doing so in this case - I cannot explain the water intrusion so I deemed it necessary to take the extra step to make the connection as water resistant as possible. I used Motorcraft electrical grease which is intended for use on connectors and terminals. I can see someone using dielectric grease which is intended for use in high voltage applications which is not appropriate here.

For example, this warning DOES make sense: "NOTICE: Do not use silicone based sprays or lubricants on any components installed onto or around the diesel exhaust system or intake air distribution and filtering system. Silicone reacts with the Nitrogen Oxides (NOx) sensors and may cause permanent damage to the NOx sensors."

But since this topic is about the harness and not the sensor installed on the catalyst... it's as Brad stated.

forddieseldoctor · July 22, 2017

What the book wants and what the book gets don't always coincide.

I understand that, but I was still bringing it up as a question to see if Keith knew something I didn't.

jimmy57 · July 22, 2017

If the reference air sampling comes through wires, which is common, the grease can poison the ceramic bits in sensor tip. The wire insulation will hold it in and the stuff will travel. High temp DG shouldn't become liquid so maybe it is a low or even no risk.

Keith Browning · July 23, 2017

If the reference air sampling comes through wires, which is common, the grease can poison the ceramic bits in sensor tip. The wire insulation will hold it in and the stuff will travel. High temp DG shouldn't become liquid so maybe it is a low or even no risk.

Sounds like you have some knowledge on this and what you stated makes sense. BUT. In this instance, the connector that got the electrical grease was the NOx module. The sensor is connected to the other side of the module which I assume is either hard wired to the module or a non-removable connector. Point being that there is a circuit board between the module connector and the sensor that would make any direct transfer of silica to the sensor itself highly unlikely. I would think. :chinrub2: This discussion is exactly why I get frustrated with Ford for not explaining their warning for better clarity.

jimmy57 · July 23, 2017

I've only ever seen the warning for this for the sensor leads only.

Some brands have had oxygen sensor poisoning repeatedly until they figured out the heated PCV nipples were allowing oil to travel to sensors via wire. All that sealing of connectors and shrink wrapping of splices made for a nice path to let the oil migrate. And what is the lowest parts in a fuel system and the item that doesn't like oil. I have never seen any explanation of why vents on the sensors as originally done was abandoned in favor of the reference air going remote through wires.