Common Failures When do you see failures in the DOC? Typically, it is not the DOC that fails, but a failure happens upstream. This causes the DOC to stop working and you get cool regeneration. Common DOC Failures The HC injector clogged: Fuel can mix with soot to clog the injector. EGR coolant leaks & turbo fails: Oil and coolant sent downstream will contaminate the PGM coating, leading to DOC inactivity. An inactive DOC will struggle to raise the temperature needed for a proper regeneration. The air filter is full: The DOC needs air when it ramps up to go through regeneration. If the air filter is full or clogged, the DOC can not get air. When do you see failures in the DPF? DPF can fail due to failures upstream or due to high mileage, then it get full with soot and ash. Common DPF Failures Engine and Fuel system failures: Fuel or oil can mix with soot to clog the DPF. EGR coolant leaks & turbo fails: Oil and coolant sent downstream will contaminate the PGM coating. Air induction system failure: Incorrect air amount in engine lead to excess soot. Milege and replacement intervals: DPF like each filter has limited lifetime. We recommend to cheange DPF after every 200,000km on distribution vehicles and after every 400,000km on long distance vehicles. When do you see failure s in the SCR? Typically, for SCR failures root cause is in other system failures. Common Failures causing problems with SCR Failures in DEF system: Incorrect work of DEF system can cause damages on SCR. Failures upstream: SCR can be impacted not only by engine and it system failures, but also DOC and DPF failures. Mechanical defects of substrate: Often substrate slides out of canning or get some cracks. 3
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