P2080

P2080 sets when the upstream EGT 1 sensor on Bank 1 (typically pre-turbo or pre-DOC) reports a value that disagrees with the ECM's thermal model for the current fuel rate and engine load - it is a rationality fault, not an open/short fault. Cheapest-first ladder: at key-on engine-off, EGT 1 should sit within 10 C of intake air temp and coolant temp; if it reads 200 C cold or stuck at -40, the sensor or wiring is the issue. At idle after warm-up, EGT 1 should read 200 to 350 C on a diesel; under a 60 mph cruise it should be 350 to 500 C, and during commanded regen it should climb to 550 to 700 C. Caveat: a soot-coated probe tip lags real temperature by 20 to 60 seconds and will set P2080 only under transient load - cleaning the probe with a wire brush and brake cleaner often clears the code for 10,000+ miles before recurrence.

Vehicle-specific patterns: 2008 to 2010 Ford 6.4L Powerstroke set P2080 from the EGT 11 pre-DOC sensor soot-coating after stacked regens, Ford TSB 10-4-6 covers cleaning procedure before replacement; 2007.5 to 2012 Dodge 6.7L Cummins suffer P2080 from the pre-turbo EGT sensor cracking from vibration; 2014 to 2018 Ram EcoDiesel 3.0L set the code from coolant intrusion at the sensor connector after a known EGR cooler failure. Estimated repair: $0 to $420.