GM service bulletin: GMC Sierra 1500 Duramax LZ0 coolant fix
GM addresses coolant valve fault on 2023 GMC Sierra 1500 Duramax LZ0
GM service bulletin: GMC Sierra 1500 Duramax LZ0 coolant fix
GM issues a service bulletin for 2023 GMC Sierra 1500 Duramax LZ0 over a faulty coolant valve. Free repair and coolant refill, warranty to 15 years/240,000 km.
2025-09-22T13:05:54+03:00
2025-09-22T13:05:54+03:00
2025-09-22T13:05:54+03:00
General Motors has issued a special service bulletin for select 2023 GMC Sierra 1500 pickups equipped with the Duramax LZ0 diesel. The concern is a potential fault in the coolant control valve that can trigger the check-engine light and leave the cooling fans running even after the engine is shut off.Covered under program N252508340 are trucks with the 3.0‑liter inline-six Duramax, rated at 305 hp and 671 Nm of torque. This engine replaced the LM2 and is paired with a 10‑speed automatic transmission.Owners are being offered a free replacement of the valve, a new oil dipstick seal, and a refill of the system with new coolant. Warranty coverage is extended to 15 years or 240,000 km, regardless of ownership history. Those who have already paid for repairs can apply for reimbursement through October 31, 2026.GM notes that a dealer visit is necessary only if symptoms are present. Because parts are limited, repairs are handled by special order. Owners can get additional details through GM customer support.The campaign is designed to reduce risk for customers and reinforce confidence in the new diesel, often referred to as the baby Duramax. The approach feels pragmatic: prioritize trucks that actually show the issue, back it with long coverage, and keep buyers at ease as the LZ0 builds its reputation.
GM, General Motors, GMC Sierra 1500, 2023 GMC Sierra, Duramax LZ0, service bulletin, coolant valve fault, check engine light, cooling fans, warranty extension, free repair, reimbursement, N252508340
2025
Michael Powers
news
GM addresses coolant valve fault on 2023 GMC Sierra 1500 Duramax LZ0
GM issues a service bulletin for 2023 GMC Sierra 1500 Duramax LZ0 over a faulty coolant valve. Free repair and coolant refill, warranty to 15 years/240,000 km.
Michael Powers, Editor
General Motors has issued a special service bulletin for select 2023 GMC Sierra 1500 pickups equipped with the Duramax LZ0 diesel. The concern is a potential fault in the coolant control valve that can trigger the check-engine light and leave the cooling fans running even after the engine is shut off.
Covered under program N252508340 are trucks with the 3.0‑liter inline-six Duramax, rated at 305 hp and 671 Nm of torque. This engine replaced the LM2 and is paired with a 10‑speed automatic transmission.
Owners are being offered a free replacement of the valve, a new oil dipstick seal, and a refill of the system with new coolant. Warranty coverage is extended to 15 years or 240,000 km, regardless of ownership history. Those who have already paid for repairs can apply for reimbursement through October 31, 2026.
GM notes that a dealer visit is necessary only if symptoms are present. Because parts are limited, repairs are handled by special order. Owners can get additional details through GM customer support.
The campaign is designed to reduce risk for customers and reinforce confidence in the new diesel, often referred to as the baby Duramax. The approach feels pragmatic: prioritize trucks that actually show the issue, back it with long coverage, and keep buyers at ease as the LZ0 builds its reputation.
