← Power loss / limp mode on all engines
Symptoms · Duramax 3.0 (LM2/LZ0)
Duramax 3.0 (LM2/LZ0): loss of power, limp mode or derate
7 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.
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.
verified
How widespread: Very common
How it shows up
- constant high-running radiator fan, fluctuating temperature, 'Engine Power Reduced' message
Its other signs
- P1098 (and neighboring circuit codes); temperature spikes past 210F in traffic
- some trucks fail repeatedly; GM Special Coverage N252508341 (09.2025) covers the valve only when onboard diagnostics confirm it as the root cause
How to tell it apart
- P1098 + fan/temp behavior isolates the valve circuit; inspect the harness connector for corrosion before ordering the valve (forum-documented split)
- check Special Coverage N252508341 eligibility by VIN before paying out of pocket (owner reports of inconsistent VIN coverage)
Usual fix
replace the coolant flow control valve (check the special-coverage window first; the harness-connector corrosion variant is repair work on the valve circuit - no separate catalog part)
Recalls and bulletins
N252508341
Root cause, parts and sources →
verified
How widespread: Common
How it shows up
- 'Exhaust Fluid System' / DEF quality warnings, countdown to speed limitation
- hard 5-mph derate when ignored; NOx codes accompany tank-side heater/pump faults
How to tell it apart
- read the DEF/NOx codes together: tank-side heater/pump codes before sensor codes
- verify DEF quality/fill before replacing hardware (contaminated or frozen fluid mimics hardware faults)
Usual fix
replace the DEF tank heater / pump-delivery module when codes point at the tank side
Root cause, parts and sources →
aggregated
How widespread: Occasional
How it shows up
- power loss / derate when ash-loaded beyond limits
Its other signs
- regen not completing / frequent regens, DPF differential-pressure codes
How to tell it apart
- check regen history/soot load before replacing hardware; short-trip duty cycles explain most frequent-regen complaints
Usual fix
off-truck DPF cleaning when ash-loaded (service item)
Root cause, parts and sources →
verified
How widespread: Occasional
How it shows up
- check engine / 'Service Emission System' message, often with a speed limitation (65 mph) derate
Its other signs
- EGR cooler failure: slow coolant loss with no visible puddle, sometimes white smoke on cold starts
- recurring CEL that a dealer clears rather than fixes (owner-reported pattern)
How to tell it apart
- read codes first: P2C7A and EGR-related P-codes split the valve/cooler path
- coolant dropping with no external leak points at the EGR cooler (pressure-test, inspect; see also the coolant control valve record)
Usual fix
replace the EGR valve (the derate usually lifts once the valve/harness fault clears; wiring-harness faults are splice repair work - no catalog part)
Recalls and bulletins
TSB MC-10165111
Root cause, parts and sources →
aggregated
How widespread: Occasional
How it shows up
- noise from the bellhousing area, oil-pressure code P06DD, 'Reduced acceleration' message
Its other signs
- sudden engine failure at low mileage (owners report failures under 12,000 miles); engine replacement under warranty with long waits
How to tell it apart
- ask whether bulletin 25-NA-307 was performed; bulletins do not notify owners
- listen for bellhousing-area noise and read stored codes (P06DD)
- a dealer measures crankshaft end play per the bulletin
Usual fix
dealer inspection and thrust bearing repair per TSB 25-NA-307; engine replacement under warranty when damaged
Recalls and bulletins
TSB 25-NA-307
Root cause, parts and sources →
aggregated
How widespread: Occasional
How it shows up
- may accompany the DEF derate ladder when SCR efficiency reads low
Its other signs
- P20EE (NOx catalyst efficiency) and NOx sensor circuit codes, CEL
How to tell it apart
- confirm which sensor position is coded before ordering (GM splits position 1/2)
Usual fix
replace the coded NOx sensor (position split per GM)
Root cause, parts and sources →
aggregated
How widespread: Occasional
How it shows up
- underboost/overboost codes (P0299 family), smoke, power loss
Its other signs
- coolant loss traced to the hard coolant line to the turbo (community-documented)
How to tell it apart
- smoke-test the boost path before condemning the turbo (underboost is often a pipe/clamp)
- check the turbo coolant line when coolant loss coincides with turbo-area residue
Usual fix
replace the turbocharger (or have it rebuilt) when the wheel/housing is the fault; the diesel coolant-line rows are not carded in the dealer catalog (the 2.7L gas rows are - do not cross-order)
Root cause, parts and sources →
Other symptoms on the Duramax 3.0 (LM2/LZ0)
Losing coolantDEF, DPF and regeneration warnings
Everything on the Duramax 3.0 (LM2/LZ0)Its recalls and bulletins