ECM Code P21DD
 

Good morning,

My 2015 Express EWB w/ 6.6L Dmax (LGH) threw the reductant heater code, P21DD, yesterday. I wanted to make sure those of you with a Chevy diesel are aware of the Special Coverage Bulletin No.: 29400-01 dated: November 2017 specifically extending the warranty on this item to 120,000 miles as a known issue; there's even reimbursement for those who have paid out of pocket to correct the issue. Chevy Special Coverage https://gm.oemdtc.com/6957/special-coverage-diesel-emission-fluid-tank-reservoir-2013-2015-chevrolet-gmc