Recipe - GM 3.0L Duramax LM2/LZ0 I6 (2020+)
Specific Fix build
Reliability tier: verified - verify before ordering, see /disclosure/
Coolant flow control valve job for the 3.0L Duramax (mode Coolant flow control valve failure (active thermal management)): high fan, fluctuating temp, P1098, 'Engine Power Reduced'. Two failure layers - the actuator harness connector corrodes (the cheap fix) and the valve itself sticks (the $322 part). Check the GM Special Coverage N252508341 window by VIN BEFORE paying: GM extended coverage in 09.2025, but only when the diagnostics confirm the valve.
Parts
- 3.0L Duramax Engine Coolant Flow Control Valve (GM 24001355) - the flow control valve itself (24001355, covers every body line 2020-2024; 2025+ rides successor 40009644) (qty 1)
Install order
- read codes: P1098 + the fan/temp behavior isolates the valve circuit
- check Special Coverage N252508341 eligibility by VIN at a dealer - the repair may be free (owner reports of inconsistent VIN coverage: get the denial in writing)
- inspect the actuator harness connector for corrosion first - the forum-documented split; a corroded connector mimics the valve
- replace the valve, refill and bleed the cooling system, clear codes and confirm the fan cycles normally
Expected outcome
Parts budget
About $330 in parts. Prices marked "at Dave's" are Dave's Auto Center's, the same as in his store; the others are approximate prices from OEM and maker catalogs, rounded (a manufacturer's list price can run higher). Parts only, no labor.