Is it an O2 sensor problem?
I have a 2002 Mazda 626 with about 140k miles on it. Last winter (2014-2015), I noticed
that it was idling rough. I noticed a faint smell coming from, what seemed like my vents. It
smelled almost like a blown out candle. Eventually, when the car was idling (at stop signs,
red lights, etc.), the check engine light would flash, and as soon as I stepped on the gas
again, the check engine light would either shut off or stay steady. I was always told that if
your check engine light flashes, you better pull over or you could cause serious damage.
So, considering I was (and still am) a broke college student, I could not afford to even
have the car looked at by a mechanic, let alone to repair what was wrong (I am very naive
when it comes to car issues and, after 2 transmission rebuilds and replacements, I had
always assumed repairing a car will never cost less than $1000). Because of this "fear"
and lack of money, I stopped driving it and basically let it sit throughout the rest of the
winter, starting it up every now and then. I KNOW THIS WAS A MISTAKE!!! I know this
because about 2 weeks ago, I finally had it towed and when they started it up and towed
it, my alternator was "locked up" and busted the belt (made a god-awful sound too). This
was a $500 mistake and I have paid for it.
I gave the mechanics the codes and everything and they pretty much disregarded what I
told them because it was clear to them that the alternator and belt needed to be replaced.
Which, yes, it needed to be replaced, but they did not address my original problem of the
rough idle, etc., which is WHY I had it sitting for so long. They basically told me I was
crazy and that everything would be fine after I got the new alternator. I don't know much
about cars, but I knew they were wrong. They did not check my O2 sensor which is what I
was told could be the problem.
Before I let the car sit, I did take it to AutoZone to get codes pulled. This is what they gave
me: P0172 (air fuel ratio) and P0136 (heated oxygen sensor).
I got my car back a few days ago, and to my surprise, it ran great. Until today. I noticed it
was shifting a little harder than usual, but with the problems I've had in the past with this
vehicle, I brushed it off. Once I was almost home, the hard-shifting turned into severe
jerking and jolting and the check engine light came on. No other symptoms other than
that. I have no rough idle anymore, just rough shifting of the gears.
Basically, my question is: Do you think this is actually an O2 sensor issue? Is it possible to
have different, intermittent symptoms that stem from the same problem? Like I said, I don't
know much about cars and this whole post might not even make sense, but I'm really sick
of having my car repaired and then a month later, something else goes wrong. I have
officially put more into this car than I paid for it, but I cannot afford a new one at the time.
I'm a mess.
