Greetings,

I have a 2012 Mazda 3, SkyActive 2.0. I presently have 64,000 miles on it. About six thousand miles back, and about 7 months ago I noticed my gas mileage falling. With a 17 mile one-way drive to work, half freeway, and half side streets I would average 34 MPG. Now, I am averaging about 30.3 MPG. I replaced the spark plugs with iridium plugs - and I did not gape them, because I read that iridiums don't need to be gaped. These new plugs did nothing for the mileage. One symptom is that it is not shifting properly in automatic mode. At first I could feel it, then I would go to manual and find it was in 5th gear going down a sloped road. The idle levels out to 800 RPM when started cold.

Another symptom I noticed, and found in the Mazda 3 forums... My headlights will intermittently flicker when applying the brakes. I saw the forum thread on this issue and saw that it was a software update. Could the poor mileage be a similar software fix? I really do not trust the dealerships to get an honest answer. I live in Southern California, where top dollar service charges are always standard.

I would appreciate any/all input on this issue.

Thanks,

Richard

 

Why don't you trust the dealerships?

 

I didn't post a question to get a question, however -
I don't trust dealerships to provide a fair cost for a service. example - when I was looking to replace spark plugs on my 3 they wanted $180!!! $24.00 in spark plugs. So, they are getting a $156.00 for 20 minutes of work? At Toyota I took in my 2006 Tundra (37,000 miles) for a airbag recall and they did free inspection. They way they talked up my trucks needs was embarrassing. cracks in the belt - none. Everything to jack up cost. I typically trust independent mechanics, and I have a great one, however, he is 30 miles away from home. He won't jack up the costs. However, he may note know about code alerts. Again, I don't trust dealers to give me an honest "need/cost assessment."

 

When did the vehicle last go to a dealership for a software update?

I would get a code check done. ( Mazda's own tester "MMDS" reads more codes & more detail than aftermarket scanners)

followed by,

Disconnect the battery, Clean the MAF, Clean the throttle body. Reconnect the battery. Start it up, A/C off, let it idle for a few minutes then go for a gentle drive to relearn your driving style.