The engine reduced power pops up on a 2007 Chevrolet Tahoe. I tried changing the MAF but couldn’t get it off. What’s my options?
– Kevin H.
Unfortunately, that’s not going to be enough information for me to truly help you, but let’s see what we can come up with. Obviously there will be some guessing on my part.
I can confirm that when the reduced power indicator appears, the vehicle’s Powertrain Control Module (PCM) has detected a serious problem. The reduction of engine power and subsequent warning light is to strongly encourage you to go in for a service and prevent drivetrain or engine damage. When your engine’s reduced power warning illuminates it could be for a multitude of reasons, even an overheating engine can cause this.
My first assumption is going to be that along with the reduced power sign there is also a Malfunction Engine Light (MIL) appearing. Because you have already tried replacing the Mass Air Flow (MAF) sensor, I am also going to further assume that the trouble code stored in the PCM was related to the MAF. The MAF sensor measures the volume of air entering the engine.
Because you have changed the MAF sensor, you should be now looking elsewhere. You could have a wiring issue related to that sensor, but commonly a MAF error code represents an intake system air leak.
As simply as I can, the MAF sensor is measuring the incoming air, but if air is getting into the engine somehow bypassing the MAF sensor, then other downstream sensors will see this extra air and a related trouble code will appear in the PCM. Check the rubber and plastic air piping in the throttle body area for breaks or a broken vacuum line. Of course, the manifold gaskets themselves may be leaking. Most repair facilities will use a smoke machine to look for leaks. With the engine off a technician will inject a small amount of smoke under pressure into the intake system and then use a bright light to look for any escaping smoke. If smoke is leaking out, then it can be concluded that air is also being sucked in when the engine is running.
Lou Trottier is owner-operator of All About Imports in Mississauga. Have a question about maintenance and repair? E-mail globedrive@globeandmail.com, placing “Lou’s Garage” in the subject line.
Shopping for a new car? Check out the new Globe Drive Build and Price Tool to see the latest discounts, rebates and rates on new cars, trucks and SUVs. Click here to get your price.