P2084

P2084 is the Bank 2 EGT 1 rationality fault and only appears on V-engine diesels with banked exhaust temperature monitoring upstream of each turbo or DOC. Cheapest-first ladder: with the engine off and cold-soaked overnight, EGT 1 Bank 1 and EGT 1 Bank 2 must read within 15 C of each other and within 10 C of IAT; any larger spread points to one sensor or one harness leg. Warm idle should show both banks within 40 C of each other, and a balanced cruise should hold them within 50 C. If Bank 2 lags Bank 1 by more than 60 C under steady cruise, suspect a Bank 2 injector underfueling before condemning the sensor. Caveat: many V8 diesels route the Bank 2 EGT harness directly over the turbo Y-pipe, and the insulation degrades in 60,000 to 80,000 miles.

Vehicle-specific patterns: 2008 to 2010 Ford 6.4L Powerstroke fail Bank 2 EGT 11 from heat damage near the up-pipe; 2011 to 2016 Duramax LML 2500/3500HD set P2084 when the passenger-side EGT 1 sensor connector backs out from vibration; 2011 to 2019 Ford 6.7L Powerstroke set the code from Bank 2 EGT sensor failure during the first regen cycle after a cold soak below -10 C; 2007 to 2012 Mercedes ML320/350 BlueTEC OM642 set P2084 from the right-bank EGT sensor cracking inside its housing. Estimated repair: $110 to $510.