Cylinder deactivation is a technology used for fuel economy, removing one or more cylinders from the equation under light load in order to improve vehicle efficiency. But if it goes wrong, some gnarly things can happen, which is the reason for Mazda's latest recall.
Mazda announced this week that it has issued a recall for approximately 262,000 cars and SUVs. The vehicles included in this recall are the 2018-2019 CX-5, the 2018-2019 Mazda6 and the 2019 Mazda3. Nearly all of the vehicles were built at Mazda's factory in Japan, with the exception of 2,651 Mazda3s that were built in Mexico.
The cars' cylinder deactivation tech is at the root of the issue. When transitioning from cylinder deactivation to full cylinder activation, a powertrain control module in charge of the hydraulic valve clearance adjuster might function incorrectly. If that happens, the intake valve rocker arm might leave its usual position and bump into other engine components.
If this happens, the engine may misfire or lose power, and a warning light might illuminate on the dashboard. The engine also has a chance of stalling without the ability to restart. Any of this can increase the risk of a crash while the vehicle is traveling at speed. Thankfully, Mazda said it has received no reports of accidents or injuries stemming from the problem.
Mazda did not specify a timetable for the recall, nor did it explain how it will remedy the situation. Since the automaker only just filed its 573 defect notification with the federal government, there may be some time before that information comes to light. Considering the issues appears to be software-based, hopefully a reflash of the powertrain control module in question will clean things up. As always, owners will eventually receive a recall notification from Mazda via first-class mail.