Kenworth T680 SPN 1046 FMI 2 Engine EGR Mixer Temp Sensor Data Erratic

Question

I am getting a recurring fault for the EGR mixer temperature on my Paccar MX-13. The truck is derating under heavy loads and the intake temps on my scan tool are jumping from 140 degrees to 400 degrees instantly. It seems to happen more frequently when I hit bumps or at high RPM.

Carlos Diaz · Accepted Answer

The issue was a failing EGR Mixer Temperature Sensor, part number 2104839. I replaced the sensor and noticed the pigtail was brittle from heat soak, so I spliced in a new connector kit (Part #2040523). After clearing the codes and performing a forced DPF regen to reset the derate timers, the truck has been running 3,000 miles without the code returning. The sensor was about $115 and the pigtail was $45.

Greg Walters · Answer

I had this exact issue last month. It turned out to be the 5-volt reference wire rubbing against the back of the cylinder head. It didn't look bad at first glance but it was shorting to ground periodically.

hd_trucker_77 · Answer

You need to perform a resistance test on the sensor itself while it is cold and while it is hot. If the readings don't follow a smooth curve, the internal thermistor is failing. Also, check your EGR valve for stickiness as it might be dumping too much heat into the mixer.

turbo_tony · Answer

Check the pins inside the harness connector very closely. These Paccar looms are notorious for 'pin push-out' where the female terminal backs out of the plastic housing, causing an intermittent open circuit.

Kenworth T680 SPN 1046 FMI 2 Engine EGR Mixer Temp Sensor Data Erratic

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