2005 Mazda 6, 2.3L 4 cylinder
Engine light comes on periodically for past month always showing code P0340, I've had the camshaft position sensor replaced, light came on throwing same codes, upon further inspection found timing was off by 2 teeth. Took car to Mazda dealer had valve cover replaced, oil changed, had timing chain reset and had camshaft position sensor replaced for the second time.
Engine light came on again tonight throwing same code now a month and about $1200 later. Any ideas?

 

There's was a bulletin (2004) out in my market for pre-facelift GG & GY Mazda 6's. It mentioned incorrect chain timing & also a Malfunction in the CKP ( Crank Position Sensor )

 

 

It wasn't a recall, jusy a tech bulletin in my market, note: I'm not in the USA or Canada

You can confirm both the cam & crank sensors were replaced?

 

Ah I see, so i was able to get in touch with my tech today, he confirmed that the timing chain was perfectly fine, which is why he opted to reset it rather than replace it. Also while the camshaft position sensor was replaced and is brand new, the crankshaft position sensor has never been replaced and is the original one that came with the car. I think it might be more cost effective to replace that crankshaft sensor around $350 USD. Otherwise I'll be paying hourly for mazda to look through the wiring of the engine harness scouring for open, or shorted circuits. By the way its worth mentioning, the ECM (computer) the battery and the alternator have all been replaced within the past year.

Also im at 94k miles, transmission fluid is (allegedly) burnt, and has never been replaced. I have called and asked a handful of mechanics and Mazda dealers in the New York and tri-state area and I have heard mixed reviews, more than half of them say don't bother changing the transmission (transaxle) fluid as its already too late they say if i change it ill end up needing a new transmission very soon, as its already too far-gone, they insist that I just ride it out and I could end up getting considerable more time out of it before it goes. While a handful of mechanics told me that I should change it, saying I may have a chance especially if I use some of the Lucas transmission additive which is supposedly very good for older transmission and may do the trick.
Either way i feel like im on thin ice with this piece of **** car, i've never owned a car that was like this before in my life.

 

For peace of mind and longevity, the trans fluid should be changed every 40 to 50,000 miles.

Yes if its flushed now, you could stir up crap & kill the trans now, on the other hand, flushing it may save it & prolong its life.