One of the most common problems on a 6.7L Powerstroke is failure of the exhaust gas temperature sensors. Some of you may be running out of the extended warranty and will have to start doing these yourselves. Others just do not trust a dealer to work on your vehicle. Some dealers will even let you order the parts and install them yourselves and still be covered under warranty. Maybe you are stuck stranded somewhere with no other choice than to change it yourself. Regardless of the reason, I'll show you how to change your exhaust gas temperature sensors.
From this point forward, we will refer to the exhaust gas temperature sensor as EGT. Before we get into how you go about replacing your EGTs, you should probably understand what exactly their purpose is.
Their purpose is a pretty simple task of measuring the temperature of the exhaust gases at different stages in the exhaust treatment process. This is done to determine the effectiveness of the different stages and to monitor for over temperature conditions that would damage the exhaust. There are a total of 4 EGT sensors on the 6.7L Powerstroke. The digits after the EGT, such as EGT12, is how the computer determines where each sensor is located. When you see EGT12, it literally stands for "exhaust gas temperature sensor bank one sensor two".
EGT11 monitors before DOC
EGT12 monitors after DOC
EGT13 monitors after SCR
EGT14 monitors after DPF
All those fancy fancy acronyms actually mean something. The DOC is the Diesel Oxidation Catalyst, DPF is the diesel particulate filter, and SCR is the selective catalyst reduction. The DOC oxidizes the hyrdocarbons to burn and heat the entire exhaust system. When the truck enters active regeneration, it dumps extra fuel into the exhaust causing the DOC to create extreme temperatures to burn the trapped particulates in the DPF. The SCR is used to inject diesel exhaust fluid, or DEF, into the exhaust to convert harmful NOX emissions to something stable. I hope you slightly understand at least why EGT are important.
(Note: The location of EGT12 and EGT13 is reversed in narrow frame chassis cab.)
EGT replacement on a 6.7L Powerstroke diesel is rather easy if all goes according to plan. The first thing you need to do is make sure you have the available parts on hand to complete the repair, 6.7L EGT Sensor. determine which exhaust gas temperature sensor needs to be replaced. You will need a way to scan the truck. I assume you already did this and that is how you have determined your EGT's are bad. Depending on which DTC's has been displayed will direct you to which EGT sensor needs replaced like mentioned above.
The EGT location on the 6.7L Powerstroke is easily determined even if you do not know what each component looks like. So if you have a code for EGT12, it is the second EGT in order from the front of the exhaust system. It's as simple as that. Be sure you are not counting the other exhaust sensors like the differential pressure sensor or the NoX sensors.
There are two likely outcomes to removing the EGT sensors. Best case scenario: they will likely be hard to unscrew but hopefully they will come out without much fuss. Or worst case: it will not unscrew or pulls the threads right of the the exhaust with it. If that happens, you will need a bottoming tap to repair the exhaust.
Removing the EGT with a wrench seems like the best option, but that is far from the truth. You will want to cut the sensor off close to the nut and use a 6 point socket and long ratchet to remove it so you have less likely chance of rounding off the sensor. The picture in this article will show you what that should look like. Of course you will need a wrench for installation of a new sensor - I find it rather ineffective to cut the top off of a new sensor...
I have got to head to work and find a tap size for you if you need to do it. Ill keep you posted on that.
After changing the EGT sensor, all you need to do is clear the codes and start your 6.7L Powerstroke up. Please keep in mind that if you have the sensor disconnected and start the truck, it will not restart after you turn it back off until you wait at least one hour. That is an unavoidable fail-safe for an emissions violation that even a scan tool can not clear.