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For the used-truck buyer

Duramax LML vs L5P, compared

The LML is the only Duramax with the Bosch CP4.2 pump; the L5P replaced it with a Denso HP4. Both carry DEF, SCR and a DPF. What fails, what was recalled, what the repairs cost, with sources and no verdicts.

At a glance

The identity rows are facts from our platform records; the counts are what this site documents for each engine today.

One engine generation each: the LML's 2015 change is the body, not the engine; the L5P's 2024 Gen2 is a calibration and supporting-hardware refresh. The CP4.2 is the line between them that matters most to a buyer: a contaminated CP4.2 sends metal through the whole fuel system. Recall counts follow the years each engine was sold: a longer run collects more campaigns.

What fails, engine by engine

Most widespread first. Each failure links to its full record (symptoms, cause, diagnosis, fixes, sources). Complaint counts are NHTSA owner complaints matched to that failure by keyword (unadjudicated) and only compare failures on the same engine, not engines with each other. How we tier facts.

Same symptom, each engine

How many documented failures show each sign on each engine, and the most widespread one. Open a cell for every cause on that engine, ranked, with how to tell them apart.

Safety recalls

NHTSA safety recalls whose text names the engine, newest first, with NHTSA's own risk statement. Bulletins and programs are on each engine's recall page.

A recall's remedy is free. Whether one is still open on a given truck is a VIN question: check at nhtsa.gov/recalls before paying for the same work.

Repair costs, in money

Parts budgets from our repair recipes, for the failures a recipe prices: Dave's Auto Center's prices where Dave's lists the part, approximate OEM and maker catalog prices (rounded) for the rest. Labor not included; not a quote.

Method: built from the same records as the engine pages on 2026-11-01. Failure modes are tiered and sourced per record and ranked by how widespread they are; complaint counts come from keyword classification of NHTSA owner complaints (unadjudicated); recalls are NHTSA's records for the models and years each engine was sold in; budgets are our repair recipes' bands at their check-date prices. No verdicts here, documented risk only. Full disclosure model.