At 125,000 miles, the CEL came on and the code is P0016, which is for the timing chain has stretched and jumped a tooth. The engine was new in 2019 and in 2021, they redesigned the timing chains due to early failure. The oil pump belt is listed for inspection/replacement at 150,000 miles, but the timing chain ds not give any interval for replacement and should easily outlast the oil pump belt to at least 250,000 miles. GM knows that there is a timing chain issue with the 3.0 Duramax LM2 engine and it is costing owners between, $7,800 and $10,000 to repair.