There appear to be 2 major reasons for turbocharger failure and Mazda CX-7 issues. The 2.3L petrol has 1) has known issues with the VVT actuator and 2) the motor runs hot. Both contribute to turbocharger issues and can cause complete engine failure. The VVT actuator uses oil pressure to change camshaft positions in the engine. Dec 19, 2018 · EGR valve failures causing the code P0401 were common in the Mazda CX-7 vehicles with a 2.3L turbo engine. In many Mazda/Ford 4-cylinder engines, the code P0401 can be caused by a sticking EGR valve. The EGR valve must be replaced to repair the problem. Not all EGR problems are caused by a failed EGR valve. Aug 9, 2020 · 2007 Mazda CX 7 engine problems. Unfortunately, most reported 2007 Mazda CX 7 problems have to do with the engine, which requires very high repair costs and might suggest staying away from this vehicle. 2007 Mazda CX 7 engine problems are either related to issues with the engine timing chain, turbo problems, power loss, ticking noise, and others. Sep 10, 2022 · 3. Bad Fuel Economy. Another symptom of wastegate stuck on closed is a poor fuel economy. Your engine will consume more without actually being burned. The fuel will be expelled through the exhaust system. The turbo system is a great way to improve the fuel consumption of your vehicle. Once you notice that your vehicle consumes more fuel than 7lRB5.