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Symptoms · Duramax LB7-LMM (2001-2010)

Duramax LB7-LMM (2001-2010): white smoke from the exhaust

2 documented failures on this engine list this among their signs. They are ordered from the most widespread down. Each one shows the signs in its record's own words, how to tell it from the others, the usual fix and any recall or bulletin.

1. EGR cooler clogging / failure (LB7-LMM) Common
2. LB7 injector failures (the defining repair of the generation) Common

Not sure which engine you have, or want the recalls for your exact truck? Check your VIN: it names the engine and lists the campaigns for that model year. Whether a recall is still open on your VIN: nhtsa.gov/recalls.

1 EGR cooler clogging / failure (LB7-LMM)

aggregated How widespread: Common

How it shows up

• coolant loss into the exhaust (white steam) or into the degas

Its other signs

• overheating under load - the LLY-era heat reputation in the owner record
• EGR flow codes

How to tell it apart

• on heat complaints: verify cooler flow/condition before radiator conclusions
• check for coolant loss signatures into exhaust vs degas
• pressure-test the cooling system

Usual fix

service: replace clogged/leaking EGR cooler; keep the system intact and functional

Root cause, parts and sources →

2 LB7 injector failures (the defining repair of the generation)

aggregated How widespread: Common

How it shows up

• hard starts / extended crank, white smoke, rough idle on 2001-early 2004 trucks

Its other signs

• fuel dilution of the oil, cylinder contribution imbalance
• documented across the era - the history source itself cites the LB7 injector problems

How to tell it apart

• cylinder contribution test before ordering a set
• check return-flow rates per injector to isolate offenders
• on a failed injector: flush/inspect the fuel system - contamination kills the new set too

Usual fix

replace failed injector(s) or the set; keep the fuel system clean and consider contamination protection on a repair

Root cause, parts and sources →

Other symptoms on the Duramax LB7-LMM (2001-2010)

Losing coolantMisfire, rough idle, hesitation or surging

Everything on the Duramax LB7-LMM (2001-2010)Its recalls and bulletins

Order: how widespread each failure is in its record (near-universal, very common, common, occasional, rare), then the number of NHTSA owner complaints that match its keywords. Complaint counts are keyword matches, not a manual review of each complaint. A symptom listed here means the failure is documented with that sign; it is not a diagnosis of your truck. Tiers: verified, aggregated, contested, data-gap. How we tier and source facts.