Hi 2carpros in the past you have been very helpful to me. Now my daughter has a problem with her 2006 Mazda a 6, with a 2.3 size engine and the automatic transmission is doing a hard down shift when she climbs a hill(very hard, I drove it). She had it looked at, at the local Mazda dealership they said it was her o2 censor, they replaced her plugs and air filter. But first a little history of her car her auto transmission was replaced about 50,000 miles ago by the Mazda dealership (so they say) as it was still under warranty. They said it's her o2 sensor but there is no dash light on. Could it be something else like a linkage adjustment or some modulator thing? THE O2 CENSOR IS ON ORDER AND THEY ARE LETTING HER USE THE CAR UNTIL THE PART COMES IN. If you can hel pus with this it would be great. The trans oil doesn't smell that bad, it is at the proper level and the fact that she told me it was replaced sort of cancelled out a trans oil and filter change for the moment.