Some GMC Canyon and GMC Sierra 1500 owners may notice less-than-ideal performance from their cabin heater, in particular with models equipped with the 2.7L I4 L3B gasoline TurboMax engine. The culprit may be a coolant flow restriction caused by a twisted hose, or incomplete machining for the heater core feed pipe port. Now, GM has outlined a fix for technicians to implement in order to correct this issue.
This issue has been reported in 2023-through-2025 GMC Canyon and GMC Sierra 1500 pickup trucks. In affected models, the heater core may not receive a steady flow of hot coolant. If the coolant flow is obstructed, heater performance will suffer as a result.
The problem could stem from two primary issues, the first of which is a twisted or kinked coolant hose. GM has identified cases where the coolant hose becomes twisted just above the hose clamp, restricting flow. The twist can be hidden under a protective mesh cover, making it hard to spot. GM recommends that a technician inspects and repositions the hose if necessary.
Another possible issue may be a manufacturing defect in the heater core feed pipe. This pipe may have incomplete machining at the exhaust manifold outlet pipe T-fitting. If this blockage is present, technicians are advised to allow the engine to cool, disconnect the heater core feed pipe at the exhaust manifold outlet, and inspect the spigot connection for obstructions. If a machining defect is found, the exhaust manifold coolant outlet pipe should be replaced.
Owners with a 2023-through-2025 GMC Canyon or GMC Sierra 1500 equipped with the turbocharged 2.7L I4 L3B gasoline engine who have noticed weak heater performance should schedule an inspection with their local GMC dealer. To note, this issue may also affect units of the Chevy Colorado or Chevy Silverado 1500 equipped with either the turbocharged 2.7L I4 L3B gasoline engine or the turbocharged 2.7L I4 L2R gasoline engine.
Comments
I got that great GM feeling with genuine GM parts. This sounds like my 1997 Grand Am LE. Even the wiper motor went out.
Good thing GM gets near free labor from the time they pay to fix it, I’d bet mechanics will be expected to fix it but unlike everyone else overpaid to make the truck, the mechanic they’ll get to spend their time on it for almost no pay… It’s why there’s a huge shortage of mechanics and dealerships are scrambling to get work done…. they’ve tried everything short of paying a living wage.