I'm new to the forum, so bear with me while I try to explain what's happening to my Mazda. I purchased my 2006 Mazda 6 less than a year ago from the used lot of a local Kia dealer and it is currently under an extended warranty purchased through the dealership. I had not had any real problems with it until the end of October. I had gotten on the interstate to head home one afternoon and noticed immediately something was really wrong, it would barely accelerating and felt jerky. By the time I was 3 miles from home, it was bucking all over the place, not pulling hills, barely accelerate, and the CEL briefly came on and flashed. I called the dealer on Monday and was told it was safe to drive it to the shop so I took it in for repair. They replaced the #5 coil pack and all seemed well. 2 days later the CEL came back on and I took it to Autozone to have the code read as the dealer is closed on weekends. I can't recall the exact code it threw, but it was running lean on the left bank, possible vacuum leak or faulty MAF sensor. It went back to the shop on Monday and within hours was called with the news they didn't know why the light was on but it was most likely the gas cap and to pick it up. So I drove it with the light on for a month until I needed to go out of town for a funeral and rented a car as I didn't think it would make the trip... I was right, it was dead in the rental car lot. It was towed to the shop and finally heard back from the dealer a week later reporting that the starter had gone bad but still couldn't figure out the CEL. 2 weeks later they called to tell me that it was ready to be picked up and it was the O2 sensors had gone bad. I made it less than a half mile from the dealer before the light came back on and barely made it back to the shop. I also discovered that the switch on the driver's door for the power windows no longer worked. A week or 2 later the dealer called to ask if it would be okay to take it to their sister lot (Ford) as they suspected the computer was bad but didn't want to replace it just as a maybe and wanted a second opinion. I spoke with them yesterday morning and they declared that what was wrong with it was the O2 sensors... they had replaced them with aftermarket Bosch instead of the Mazda sensors. This didn't sound right to me and made a few phone calls to other mechanics and they did not think that this was the problem and they had most likely not put things back together properly when changing that #5 coil pack. it has now been in the shop for 6 weeks. Any clues what could be wrong with it before I start looking into my legal options? Could it actually be the O2 sensors? Should I throw in the towel? Just spoke with the dealer.... they are now claiming the EGR valve is leaking. Could this have been caused by shoddy work to begin with?

 

JB2000: I don't think you should be taken through the wringer like this. A lean code is not that hard to figure out. I also believe that these guys rush to replace sensors without figuring out why the sensors tell the computer there is a lean condition.

A lean condition exists if there is not enough fuel or too much air getting into the cylinder(s).
Not enough fuel has to do with fuel pressure and that can be measured.
Too much air has to do with vacuum leaks and they can be detected using a variety of methods:
Listen for hissing sounds.
Spraying carb cleaner at suspected areas while the engine idles. If the idle improves you found the location of the leak.
Smoke test: put smoke into the air intake under pressure and see where it comes out. There's your leak.

Give them one chance to redeem themselves. Then talk to other mechanics if they agree with this post. Then let them do it.

Print this out and wave it in front of them.

 

When a dealership says only Mazda O2 sensors will work it's time to move on to a new place. I found a different mazda dealer across town. I had this issue previously and put on NGK NTK O2 sensors. They are fine. You forgot to mention engine size & # cyls. Mileage? Tranny?

With that out of the way i can only give you poor advice.

EGR could be an issue, throttle body could be an issue if it's an automatic as it has reliance on the tranny and has caused issues.
Also if the following hasn't been done in last 3 years it MUST be done now: clean MAF, Throttle body, change PCV valve. The PCV valve is not on Mazda service to ever check so change it along with hose that attaches to it----pthis is a must!

 

I apologize for completely spacing on the details... it is an automatic V6 3.0 Wagon. The current mileage is approximately 110,000 miles. I have no idea if any of that maintenance has ever been performed in the past 3 years or not. I arrogantly assumed a reputable dealership would have performed all of these necessary tasks before putting it on the lot. This is currently there 4th attempt at repairing it and I would happily take it to my long time, trustworthy mechanic if it would make the 75 mile trip to his shop and I would also be content for them to tow it to the nearest Mazda dealership.... when I suggested such I was told that my warranty would not cover any outside work and I would never find any better mechanics than their's. The shop manager claimed early on that they used both the smoke method and a stethoscope to look for vacuum leaks and found none. As far as I know they haven't done anything with the MAF sensor or throttle body. I've never experienced the trademark drop in MPG that normally comes with a faulty MAF sensor. I'm trying to arm myself with as much knowledge as possible before going another round with them (as a female, it is a difficult battle to get them to take me seriously) and all advice is very appreciated. I will print out this thread for their reference as my own.

 

JB2000:

Look for a mechanic mom and pop shop in your area. Ask people at work, church, bridge club or wherever, where they take their cars and what experience they have. I bet you find an honest and good mechanic who won't take advantage of you. these guys didn't anything but place a pricetag into the windshield.

The details you provided now would suggest that you should go through a complete tune up.
Replace all 6 spark plugs and all 6 coil-on-plugs (COPs). Replace the PCV valve and hose as Noggin said. A throttle body cleaning, MAF sensor cleaning, EGR valve cleaning will help too.
Have the oil changed.
Have the transmission serviced.
Have the engine coolant replaced.
You have to assume that everything but the oil is 6+ years old.

I understand that this will cost some money, but it is necessary and it will transform your car. After this is done and the engine runs right you should be good for 30000 miles doing only oil changes. Then you need to service the transmission again.

If it is too much at once get the engine taken care of now and do the transmission service in the next 3 months.

I command you for taking charge and getting information. Oh, there is also a possibility that a leaky exhaust manifold pulls air in and triggers a lean code. The O2 sensor detects oxygen, but it won't know where it comes from. But an exhaust manifold leak usually makes the engine louder. They should have noticed that. I would get the car out of their garage now.

 

^^^^^^^^+1, What Tanprotege is saying, especially with that mileage. I have the exact same car as JB2000. These things are a necessity. Also when they change the plugs and ign coils they must remove the intake plenum to get at ones at the back. Those intake plenum seals need to be replaced as well as the throttle body gasket.
Click below for links to part of what i'm talking about:
Mahle W0133-1807640 Throttle Body Gasket | Auto Parts Warehouse
and OES Genuine W0133-1639826 Intake Plenum Gasket | Auto Parts Warehouse

 

I'll see if I can get them to tow it to my favorite mom and pop mechanic and cover all costs to repair the damage done and go ahead with all of the maintenance work it needs while it is there. I tried to convince them to do this on the day I went to pick it up and didn't make it a half mile before the problem resurfaced with no luck. I really love the car and hope that I can get it back in pristine condition. I'll keep you both updated and again thank you so much.

 

Sounds like you're having the same issues that I've been experiencing lately.

https://www.mazdaforum.com/forum/maz...3-0l-v6-30919/

 

Hey JB2000, did you find out real issue with your car?

I have 2006 Mazda 6 with about 115K miles on it. A month back I had CEL on. I took it to O'Reilly as it turned out to be Bank 1 Sensor 1. I haven't heard any hissing sound, neither i have seen the drop in the mileage. Should I jump on the low hanging fruit by changing the sensor or should I get it checked for leaks first?

 

The 2006 mazda 6 V6 3.0L has the absolute worst exhaust sytem I've ever seen. This can and has been the cause of cel codes.
READ: https://www.mazdaforum.com/forum/maz...-design-28940/